Nadal wins on one leg while Murray continues to improve

Rafael Nadal fought back the pain to beat Juan Martin Del Potro

In normal circumstances, the only story of the men's singles fourth round at Wimbledon would be Andy Murray's stunning straight sets victory over Richard Gasquet.

But Rafael Nadal's fantastic win against the inspired Juan Martin Del Potro has eclipsed it as the Spaniard was pushed to the brink and still prevailed despite a serious-looking foot injury.

Nadal is the ultimate warrior on the tennis court and in some ways we shouldn't be surprised at the stubbornness he showed to hide the severity of his injury and still win.

Even when half-fit, he is so difficult to break down and never gives his opponent an inch.

Del Potro had injury troubles of his own, breaking down mid-match with a recurrence of his hip injury, but both men played some stunning tennis throughout and it was hard to tell either of them were struggling.

It really was a brutal match and both players should be applauded for the way they handled such a war of attrition.

The standard of tennis never dropped and it could easily have gone to five sets, but Nadal won the most important points to take it in four.

Del Potro's performance confirmed his re-arrival as a major player in men's tennis after a long period out with injuries, and he now seems to have recaptured the form which took him to the US Open title in 2009.

Del Potro has won one major, the US Open in 2009

There has been a lot of talk about the 'big four' in men's tennis but Del Potro's name can again be added to that now with his great power - with his serve and groundstrokes - almost impossible to stop when he is firing.

The Argentinean more than played his part in an excellent match which had the Centre Court crowd transfixed and he looked the better player for long periods, but the class and determination of Nadal shone through when it really needed to.

It is frightening to think these two players were not fully fit as the standard was so high you can only wonder how much better they could have been without their pains.

As for Nadal, it is very easy to run out of superlatives for him.

Admiration and respect for him is continuing to grow and it is a real relief for the tournament that he was not forced to pull out with the foot injury he sustained against Del Potro.

Nadal looked set to pull out after sustaining a foot injury near the end of the first set

Nadal said afterwards he thought at the time he had broken his foot, but he showed the strength of character to continue regardless and that is what makes him a great champion.

He makes every effort both during and after matches to hide and play down his injuries as a mark of respect to his opponents, but it was clear to see this injury had hurt him.

His bad foot may affect him later in the competition - which would be good news for the likes of Andy Murray - but even if it does, you can be sure that Nadal will give it everything he has got and still produce a stellar performance. To beat Nadal, someone is still going to have to play a fantastic match.

Nadal will probably not face a tougher game than this one in the rest of the tournament yet he managed to get through it and should still be the favourite to retain his title.

He is a true legend of the game whose status is only going to continue growing and picking up a third Wimbledon crown this year is still in his sights.

He is a rock whether fully fit or not so if any player is under any illusions they will be in for an easy match against him, they can think again.

There is no better competitor than him with his grit, determination and ability to hold his nerve still making him the man to beat.

His match against Del Potro was a real baseline war of attrition yet he made it through and still looks every inch the champion.

If his injury is to hamper him in future rounds though, Andy Murray is a real contender to take his title.

Murray produced his best display of the tournament so far to beat Gasquet

His performance against Richard Gasquet was simply sublime and the fact he managed to see out the victory in straight sets and after just two hours was a real bonus as he was able to conserve energy for the even bigger tests that lie ahead.

He took his game onto another level against the Frenchman and after winning the opening set tie-break, there was only going to be one winner.

Murray is continuing to improve round by round and his serve in particular is getting better, although he will need to continue to improve it if he has any designs of winning the title.

One of his greatest strengths are his passing shots and he produced several top drawer ones against Gasquet at crucial times to leave his opponent floored.

Gasquet's sledgehammer backhand was a real factor early on but once Murray got ahead, the Frenchman looked ordinary and it was Murray's backhand which was the more influential.

Gasquet's performance level dipped after losing the first set

Gasquet is a very good player - and should be in the top eight within a year - but he was swept aside by Murray and other players would have struggled to put the Frenchman away as convincingly as this.

He has to be seen as a major contender for the title now and if he can continue this steady improvement each round he will be a tough man to beat.

The likes of Nadal, Roger Federer and Novak Djokovic will all be on the top of their games at the business end of the tournament so Murray will need to be on the top of his to stand a chance, but he should be feeling confident.

He is in his fourth consecutive Wimbledon semi-final and he has reached three Grand Slam finals, so he keeps putting himself in positions to win majors and one day that work will pay off.

His win over Gasquet was watched by Prince William and Kate Middleton and what was noticeable was that Murray seemed calm and didn't get too down on himself when points didn't go his way.

Prince William and Kate seemed to enjoy Murray's performance

Just like when the Queen watched him last year, Murray seems to be on his best behaviour when the Royal Family watch his matches and that helps to produce quality performances and less anger.

Perhaps royalty should attend all of his matches as when Murray's demeanour is positive and calm, he seems to play better.

Murray faces Feliciano Lopez - or 'Deliciano' to Murray's mum Judy - in the quarter-finals and that presents a very real opportunity to reach the semi-finals for a third year in a row.

Lopez will have to be taken very seriously as any player who makes it this far must be top quality but in reality Murray should have too much for him.

He would then be likely to face Nadal in the semis - providing the Spaniard's foot injury subsides - and that would be a daunting match. However difficult the task is though, Murray knows he is capable of beating Nadal in major tournaments (as he did in the US Open of 2008 and Australian Open of 2010).

Nadal is clearly a phenomenon and a much better player than Murray but if Murray can catch Nadal below-par and he can play exceptionally well, then he will have a chance.

Murray played excellently to beat Gasquet but can still improve, which is extremely promising.

To win the title is still a monumental task for him but he is good enough to do it and with a bit of belief, you just never know.

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Serena Williams had won the tournament on the last two occasions

When the Williams sisters fell on Monday, there was a feel of the end of an era at SW19.

The duo have won the ladies' singles Wimbledon championship for nine of the last eleven years so it was seen as something of a shock both of them were knocked out at the last 16 stage.

However, it was a major achievement for them both to reach that stage after battling back from injuries and they should both be happy with their efforts.

Serena hadn't played since this time last year after a foot injury and a blood clot on the lung while Venus had been ruled out since January, so there was an air of inevitability neither would win Wimbledon this year.

Serena, in particular, will be back stronger than ever in future Grand Slams as she showed glimpses of her greatness at SW19, and once she gets some more match fitness under her belt she is sure to win more majors.

She lost to the French woman Marion Bartoli, who played excellently to reach the quarter-finals but was today defeated by Sabine Lisicki.

'Individual' is one way to describe Bartoli's style - she bounces around and practices shots before every point - and you would not find her style in any textbooks, but it has worked for her so fair play.

She looks very eccentric on court and the fact she plays every shot double-handed limits her ability, but she showed great mental strength to beat Serena and should be given credit as Serena is an extremely difficult player to beat, fit or not.

Serena may well win more Grand Slams, but the task appears much harder for sister Venus.

Venus Williams has won Wimbledon five times

Other than Wimbledon, the 31-year-old has not won a major since 2001 and continues to be overshadowed by her sister.

She went out against Svetana Pironkova with a whimper for the second year in a row and she just seems to have a mental block against her.

Venus seemed to miss every shot she went for while Pironkova just played a steady game.

Venus is a player who appears to be on the wane and it will be extremely difficult for her to win another major.

Her sister will stand a better chance as she is still a great warrior and seems to have great motivation to again reach the top of the game. It shouldn't take her long.

Pironkova lost in the quarter-finals to Petra Kvitova and the women's tournament is really wide open now.

Maria Sharapova, Kvitova, Lisicki and Victoria Azarenka are the last four standing and while Sharapova is the favourite, it really could go to anyone.

The correct four players have reached the semi-finals as they have been the best four players throughout the tournament, and it makes for some great games.

Maria Sharapova is being tipped to take her second Wimbledon crown

Sharapova is the only one of the four to have a Grand Slam under her belt and that experience may be crucial.

Sharapova-Azarenka looks the likely final and that would be a great match, although the quality of the tennis would probably be overshadowed by the 'Battle of the grunts'.

If that is the final, there is only one thing for it: ear plugs.

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Novak Djokovic (left) and Bernard Tomic regularly practice together and will face each other in the quarter-final

Bernard Tomic's fairytale story at Wimbledon is to continue after he swept aside experienced performer Xavier Malisse in straight sets.

The 18-year-old Australian is clearly quite a talent and he is the youngest Wimbledon quarter-finalist since Boris Becker in 1986.

Becker won the tournament that year and while it is extremely unlikely Tomic will be able to repeat that feat this year, it is a great story nonetheless.

He will face great friend Novak Djokovic in the quarter-finals and that will be a very tough match due to the Serbian's excellent run of form and in reality Djokovic should have too much for him.

However, Tomic has upset the odds all the way through the tournament and would love to produce one last shock to take his place in the last four.

The Australian seems to have the game to go to the top of the sport and he is only going to get better.

His experiences at this year's Wimbledon should speed up the process of Tomic becoming a major star as he has now had a taste of what the latter stages of Grand Slams are like and will be hungry for more as soon as possible.

Tomic's progression to the last eight is the story of the tournament this year and with a bit of luck there may be another chapter yet to be written.