Terry underwent surgery on Sunday after suffering a broken cheekbone during Saturday's Barclays Premier League draw with Fulham and is the chief injury doubt ahead of the Group B encounter in Spain.

Terry took part in team training at Valencia's Mestalla stadium wearing a face mask, but Chelsea will wait before making a decision on whether their skipper will be fit to play.

"John Terry wants to play which is very good. Now we need to wait for training and then we will speak with the medical department and decide," said Grant.

"But he wants to play, which is good for us."

Blues winger Joe Cole believes it would be blow to lose Terry for the game against Valencia, which will see Chelsea return to the ground where they won 2-1 to progress through to last season's semi-finals of this competition.

"John Terry is very important, he is our captain on and off the pitch. He's our leader. He was operated on the other night and he wants to play," said Cole of his fellow England international.

Terry's value as a defender has also been noted by opponents Valencia, with the Spanish side's striker David Villa dubbing his would-be marker one of the world's leading - and bravest - stoppers.

"After the blow that he received on Saturday, there are few players in the world who could play, but he is one of them," said Spain ace Villa.

"We know that if he is not there, there will be someone else with similar characteristics, although he is one of the best in his position."

Aside from Terry, Chelsea could also call on Michael Essien for tonight's match.

The Ghanaian midfielder, whose late strike earned Chelsea that quarter-final win here last season, returns from injury.

Grant will still be without a number of senior players, including Frank Lampard, but Villa insists his side are not focussing on which Blues stars are absent.

"We are not obsessing about which players they are missing," Villa added.

"We want to play our game with the intention of overcoming them."

Chelsea go into the game knowing a good result is crucial following last month's disappointing home draw with Rosenborg in their opening Group B fixture.

In contrast, Valencia picked up an impressive three-point haul from their trip to Schalke - one of seven victories in eight competitive matches this season for Quique Sanchez Flores' side.

Grant, who replaced Jose Mourinho after the Portuguese left Chelsea following that draw with Rosenborg, is well aware of the importance of tonight's match.

"The game that is nearest is the most important, as it will be for Valencia. We must forget the fact that we lost two points in the first match and get a good result," said Grant, who insists a stylish performance is secondary to his side putting their Champions League campaign back on track.

"We want to win every game. If we can make the game exciting as well then we will do it, but we want to win tonight's game."

One of Grant's concerns heading into the clash is his side´s recent lack of goals.

Aside from a 4-0 thrashing of Hull in the Carling Cup last week, Chelsea have netted just once since August, with the solitary strike coming against Rosenborg.

"We need to play our game. We need to try and score and make the most of our opportunities, more so than we have done before," said Grant.

Club doctor Bryan English, who commissioned the making of Terry's mask, confirmed his chances of playing some part in the match were very much alive.

He told Chelsea TV: "In sport, if you get a fractured cheekbone behind a certain point you can play on.

"The chance of getting another blow on the same point is minimal so it is a very small risk.

"The reason John came off at half-time, after discussion, is that if there was another blow (in the Fulham match) it might make surgery more complex and with Valencia coming up, the decision was taken to take him off.

"He couldn't train on Monday because we had to get a protective mask moulded," English explained.

"The reason for getting it done as soon as possible is so he can be back playing, I don't know when that is going to be, but the mask needs to fit properly or another blow will just knock that piece of bone back.

"The mask will be taken on the plane with us whether he is going to play or not."

English, meanwhile, also said that Terry's England colleague Frank Lampard was approaching fitness.

"Frank is doing well. He is now four-and-a-half weeks on from injuring the main kicking muscle in the thigh.

"He is back out doing running and jumping, twisting and turning - everything except long kicking - so he's not far off."