Jose Mourinho has confirmed that Diego Costa will start for Chelsea at home to Aston Villa on Saturday but conceded he still remains concerned about the striker’s fitness. The Brazil-born Spain international suffered hamstring problems at the end of last season with Atletico Madrid, an issue which resurfaced when he was away on international duty earlier this month. Since then he has been unable to play twice in four days. At the start of a nine day spell in which Chelsea face Villa, Sporting Lisbon in the Champions League and then London rivals Arsenal back in the Premier League, Mourinho suggested Costa’s fitness has to be taken on a game-by-game basis.

“He plays tomorrow and starts without problems,” Mourinho said, reports Chelsea’s official website. “The question is always the same; can he finish the game and be in condition to play in Lisbon 48 hours later? I don’t know but at the moment I’m not thinking about Sporting or the Champions League, I’m thinking about Aston Villa and the Premier League. He plays for sure, he starts the game for sure and he’s in a very good condition to start.

“If he doesn’t play against Sporting he doesn’t play, we can play [Didier] Drogba or [Loic] Remy. Tuesday is another game, another story. I’ll play tomorrow with a team I think is the best team to win against Aston Villa. The consequences, after that, I have to face, and I have to organize the team to play against Sporting.”

There is little doubt that Mourinho will be keen to field Costa as often as possible right now. Since signing for £32 million, he has scored seven goals in just five appearances and his absence was felt in the two games he missed -- in a draw against Schalke in the Champions League and a narrow win over Bolton Wanderers in the Capital Once Cup in midweek -- when Chelsea lacked a ruthless streak.

With him in the side, Chelsea have made a strong start to the Premier League season and lead the table by three points. Still, there will be some frustration that the advantage is not even greater after conceding a late equalizer to 10-man Manchester City last Sunday. A defensive record that has seen Chelsea go five games without keeping a clean sheet has been the one negative thus far.

On Saturday they will be taking on the side that, along with Southampton, are surprisingly their closest challengers in the Premier League after five matches. Despite little optimism before the season got underway, Villa began with 10 points and just one goal conceded from four games. But after a sickness bug swept through the squad ahead of their match with Arsenal a week ago, Villa capitulated and let in three goals in just four first-half minutes.

Although Ron Vlaar remains an injury doubt, Nathan Baker, Ashley Westwood, Andreas Weimann and Darren Bent are fit to return after overcoming the illness. And manager Paul Lambert is keen for his side to learn from the mistakes made against Arsenal for the trip to Stamford Bridge.

“We were too open against Arsenal,” he said, according to Aston Villa’s official website. “We have had a chat with the lads this week. We have given them our thoughts and they agreed that they were too eager. Sometimes that happens when you're playing well - you think you can go out there and take anybody on.

“Now you pick yourself up and start again. You've got to try and get a foothold in the game and not be out of it before you've started. If we can do that, then great. I'm not going to sit here and say we're going to go there and play free-flowing attacking football. You do that and I think you'll get beaten pretty heavily.”

Prediction: Aston Villa offered precious little resistance to Arsenal after falling behind last week. While some of that may well have been down to the unfortunate illness, it remains true that Villa struggle when the onus is put on them to go forward. Thus an early goal could be significant on Saturday. When the two sides last met in March, Villa showed what they do well with a classic counter-attacking 1-0 win. But with Cesc Fabregas now adding extra creativity and dynamism and Costa providing the ruthless efficiency in front of goal, Chelsea should be capable of breaking down Villa’s defenses, especially if they are missing Vlaar.

Chelsea 3-1 Aston Villa

Kickoff time: 10 a.m. EDT

TV channel: NBC Premier League Extra Time

Live stream: NBC Sports Live Extra