By Arsenal correspondent Tony Hughes

Arsenal have been boosted by the unexpected return of Francis Coquelin as they welcome Mesut Ozil and Alexis Sanchez back into the first-team fold.

The triple boost was revealed by Arsene Wenger on Thursday morning as the Gunners step up preparations for Sunday’s Premier League showdown against Chelsea.

Midfield anchorman Francis Coquelin is a month ahead of schedule in his recovery from knee ligament damage that has sidelined him since November.

Arsenal did not expect the Frenchman to play again until at least March but he returned to training on Thursday morning as he targets a first-team return.

Speaking at his media conference on Thursday morning, Wenger gave an update on Coquelin and Danny Welbeck, who is also on the comeback trail.

“Coquelin’s back in full training today, ahead of schedule. Welbeck will be in full training next week,” explained the Arsenal manager.

Meanwhile, Wenger has confirmed that Mesut Ozil is back and Alexis Sanchez should also be fit for the clash against the champions.

Ozil missed the goal-less draw at Stoke last Sunday with what Arsenal claimed was a minor foot injury while Sanchez was deemed to be too much of a gamble to make his long-awaited return.

Wenger said: “Ozil will be available, Sanchez has the two days to prove it but I think this time will be available.

“The doubt about Alexis is linked with him having been out for a long time and the risk of a setback. To be clear on all the medical tests and after training is one thing, but you can never replicate the intensity of a big game and that is why I am cautious with him.

“We cannot afford another setback because that would mean a very long period out and we don’t want to take this gamble. But the signs he has shown in training this week are very positive.”

The Chilean has been sidelined since suffering a hamstring injury at Norwich on 29 November.

He has had a series of setbacks in his increasingly complicated recovery and, despite taking part in full training last Saturday, was deemed to be only 95 per cent fit by Wenger.

As revealed by Football Insider, the Arsenal manager is fearful that Sanchez could be out for another three months if he aggravates his hamstring problem.

Meanwhile, Eden Hazard is closing in on his comeback for the Premier League champions although Diego Costa is struggling to be available.