Cahill signing the beginning of the end for Terry at Chelsea?

John Terry may no longer be guaranteed a starting place at Chelsea

It's hard to imagine Chelsea without John Terry.

Terry has been the heartbeat of the side for over a decade, with his lionheart commitment, leadership skills and excellent defending making him an irreplaceable part of the Chelsea machine.

But this week's signing of Gary Cahill from Bolton could prove to be the beginning of the end for Terry at Stamford Bridge.

Andre Villas-Boas is trying to implement a new philosophy at Chelsea and while Terry is still central to it due to his position as 'Mr Chelsea', he can no longer be guaranteed a place in the side.

Most would expect Cahill to slot straight into the Blues' line-up at centre-back alongside Terry, but Villas-Boas has enormous faith in David Luiz, who has been a calamity at times this season.

The manager even went as far as saying Luiz will become one of the greatest central defenders in the world, which seems ridiculous given the evidence of his performances, but it does show Villas-Boas is not ready to cast him aside.

Luiz may be erratic and always prone to bringing attackers down, but Villas-Boas is almost staking his reputation on him and he is convinced he will come good.

As for Cahill, he wouldn't have joined Chelsea in a European Championship year to sit on the bench.

A decent half-season may be all he needs to secure a place in Fabio Capello's starting line-up for Poland and Ukraine, and Cahill would surely rather have had six more months of starts at Bolton than six months as a bit-part at Chelsea.

The ironic thing is that Cahill had a nightmare last six months at Bolton.

He struggled to reach the standards he had set in previous campaigns, and you only need to look at the league table to see how much he and his ex-team-mates have toiled.

However, a move to a bigger stage for Cahill was always on the cards and the switch to Stamford Bridge should bring out the best in him.

Cahill earned the move to Chelsea with four excellent years at Bolton

Cahill's big advantages over Terry are his age and his pace.

Terry has the experience and proven quality, but Cahill must be the future of Chelsea's backline.

Looking at the way Frank Lampard is slowly being sidelined by Villas-Boas, Terry must be worried.

Both men have bundles left to offer, but Villas-Boas seems ruthless and doesn't care about reputations.

If he feels Terry is no longer worthy of a starting place - as silly as that sounds - it won't take him long to wield the axe.

The high defensive line Villas-Boas adopted at the start of this season, which failed spectacularly, was clearly not suited to Terry.

If the Portuguese boss is to reapply those tactics it is clear the captain Terry will not have a place.

You only need to look at the way he ended up on his knees against Arsenal this season, leading to a crucial goal from Robin van Persie in the Gunners' 5-3 win, to see that.

Cahill would be a lot more suited to those tactics due to his pace, as would Luiz.

That must be the long-term partnership Villas-Boas is looking to and it may not be long, perhaps even as early as next season, before Terry is slowly phased out.

Villas-Boas is still under pressure at Stamford Bridge

That is all presuming Villas-Boas is kept on as manager, of course.

There are certainly no guarantees of that given Roman Abramovich's reputation for hiring and firing, but Terry should be worried for his future if Villas-Boas stays.

Terry has the race case with Anton Ferdinand still hanging over him and may have a hefty ban to serve as a result of that.

A long suspension could give Cahill and Luiz the chance to develop a partnership and if Cahill can prove himself and Luiz can cut out the erraticism, Terry could find himself as third choice defender.

For what it's worth, Terry should have a place in Chelsea's defence for at least the next four years.

He deserves that for what he has given for the club and for what he continues to give, but all good things must come to an end and he must be worrying for his future now.

Terry's game has been deteriorating for the last couple of years and this season, at least the first few months of it, he was well below his best.

Gary Cahill may not be the biggest name in the world but his arrival may prove the beginning of the end for Mr Chelsea.

For the first time in possibly a decade, John Terry has something to prove on the pitch.