How Much Longer Does Chelsea's John Terry Realistically Have at the Very Top?

Jose Mourinho has been unequivocal in his praise for John Terry this season.

"I thought he was over," the Chelsea boss recently said, recalling his return to Stamford Bridge in 2013. "Because he hadn’t played for the previous two years, two or three consecutive matches. He was not an option for the managers. He was injured. The managers preferred other players in front of him."

How things have changed.

When Chelsea take to the field against Sunderland for their final Premier League match of the season on Sunday, they will be led out by their captain.

And in the process, Terry will complete the first full season of Premier League football of his career aged 34.

Of Chelsea's current squad, only Branislav Ivanovic and Eden Hazard can match that feat, although the latter is expected to miss the Sunderland game after having his wisdom teeth removed this week.

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It's a remarkable achievement for Terry.

"I thought there was something wrong and that he couldn’t get back to his normal level," Mourinho continued. "But when I signed for Chelsea, he had one more year of contract, and I wanted to respect that year and see what was going on.

"We spoke and he knew my nature, that I owed him a lot, but I’d give him nothing he didn’t deserve. He knew that was my way of being a manager, and he was prepared already. He said he'd prove he deserves a place in the team, a very simple process. Obviously, he was fantastic.

"[...] I know that probably without him, we wouldn’t be Premier League champions."

A mark of how good Terry has been came in March, when he was rewarded with a one-year extension to remain at Stamford Bridge beyond the summer.

At the end of last season, Chelsea had yet to offer Terry the deal that saw him return to captain the club this term. There were still some questions that needed to be answered, and now they have been.

Forget age—Terry is a player with much more in him than that extra year he has been given at Chelsea.

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Midway through 2015/16, he will turn 35, yet right now, he looks stronger than he ever has. The number of appearances—48, in case you're wondering—he has racked up this campaign proves that.

Appearances are one thing; performances are another. And despite his advancing years, Terry has been among the standout defenders in England.

Indeed, he's been that good that a debate has even raged again about whether he should make a return to the England team.

Here's the thing: The whole debacle surrounding Terry's international retirement is why he's playing the football he is today. He isn't traveling across the continent for friendlies in Turin or European qualifiers in Tallinn and Basel.

While England are sweating, he's got his feet up; when Gary Cahill is off to Dublin with Roy Hodgson's men in June, Terry will be back on the beach he has been on since Chelsea secured the title.

The self-preservation has been key, so for the all the fallout of the end his international career, Terry is actually better off. And he looks it.

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Changes at Stamford Bridge have helped too. We shouldn't rule out the impact of Nemanja Matic in defensive midfield when we consider Terry's ability to play on.

Finally, Chelsea have a midfielder capable of emulating Claude Makelele, which means Terry is able to focus on his own game once more.

Because of Matic, he isn't exposed as much—his lack of pace rarely tested by strikers. Instead, he can play the game in front of him, read it and control it.

Any player good enough to do that doesn't have to worry about age—it's all in the head.

They're different players from different times, but Teddy Sheringham remained in the Premier League with West Ham United until his early 40s.

OK, so that's not exactly the very top in the way Chelsea can claim, but Sheringham was able to continue in the top flight because of the way he played. He was a clever player, a man wise to what was needed and when.

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Sheringham got by playing his game in a way few did, offering his manager something different. When we think of Terry—on this season at least—there are few capable of contributing what he does.

While Terry's that dominant figure at the back, Mourinho will always be happy. It'll keep the chequebook in the drawer, and every investment in Terry will be another investment in the academy, allowing more time for the likes of Andreas Christensen to develop into his replacement.

"If a player is not important, sooner or later, he leaves. Under me, he has had already two new contracts," Mourinho finished.

How long is a piece of string? Only Terry can answer that question.

Garry Hayes is Bleacher Report's lead Chelsea correspondent. All quotes were obtained firsthand unless otherwise noted. Follow him on Twitter @garryhayes