Villa are sweating on the availability of skipper Stiliyan Petrov for tonight’s Crystal Palace clash – but Gabby Agbonlahor is winning his race to be fit.

Petrov, who has recently played through Achilles and ankle injuries, has been laid low with a virus since playing in Sunday’s win over Burnley.

And boss Martin O’Neill admits the midfield maestro is a major doubt for the FA Cup fifth-round replay at Villa Park.

“Stiliyan is feeling pretty unwell,” said O’Neill. “He has been for a couple of days now.  We sent him home yesterday – if the game had been then he would have been struggling.

“We will see what he is like. At this minute he is a doubt for the game. We are going to have to be very strong tomorrow night to win the game.

“That would be a concern but at this moment we are at Tuesday morning so there’s still a few days to go before then. It’s not often he is hit with viruses.”

However, there was better news on Agbonlahor , who has made  encouraging progress since hobbling off with a calf problem in the weekend win over the Clarets.

“He is feeling his calf a little bit but he is very keen to play and that is always a very encouraging sign,” added the Northern Irishman.

O’Neill is confident he has enough other leaders in his side if Petrov fails to be passed fit.

“I think that has been a very big plus for us this season, particularly with the inclusion of the likes of Richard Dunne and James Collins who have come into the side,” added O’Neill.

“Dunne, even though he is kind of quiet, is almost like a natural leader in many aspects and leads by example as much as anything else.

“I think that anybody who comes into the side, the confidence that the other players are exuding now should be able to rub off.”

And O’Neill is wary of Championship side Palace’s threat, adding: “They will be relishing the thought of playing at a Premiership ground simply because it is the FA Cup and they have nothing to lose.

“They will be very determined. It is a big opportunity for them and they will come to Villa without any real fear.”