The powerful striker has made a blistering start to his Stamford Bridge career, scoring four goals in three appearances since leaving Spanish champions Atletico Madrid.
Costa, though, has been troubled by a hamstring problem and was forced to withdraw from Spain's squad during the international break.
"Diego came back injured but that was last Saturday," Chelsea manager Jose Mourinho told reporters on Friday.

"He had one week to work hard with the medical department. He has a chance to play on Saturday. We have a training session now to confirm his condition and to make the final decision,” he added.
Having made a smooth transition from La Liga to the Premier League, Mourinho was always confident Costa would adapt.
"When we bought him we were very optimistic. His profile as a player and a person makes it easy to adapt,” the Portuguese said.
"A player is also part of the team and we knew the team was going in a certain direction and waiting for a player like him to be there. His start has been good; three matches, three victories, four goals and good performances,” he added.
Mourinho also played down suggestions of a goalkeeping issue at the club after Thibaut Courtois, who has replaced Petr Cech as first-choice, signed a new five-year contract this week.
"I don't think there is any problem. Nobody would expect Courtois to come here and to stay without a new contract and in two years time to be a free agent and Chelsea to be in trouble,” said the manager.
"We have Courtois with a five-year contract which gives us that stability and security that we want to have with such a good young player. But Petr has two years left on his contract and he's a top goalkeeper,” he added.
Second-placed Swansea arrive at Stamford Bridge having won their first three league matches and Mourinho has been impressed by Garry Monk's side, especially given their surprise victory at Manchester United.
"I would expect them to have six or seven points, not nine," Mourinho said.

"But everybody knows in the Premier League any result can happen. They had a surprise result with a victory at Old Trafford. They then did what they had to do by winning two home games against teams with similar ambitions,” he added.

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