Arsenal manager Arsene Wenger has praised Diego Costa's ability to settle into the Premier League swiftly following his summer move to Chelsea from Atletico Madrid.

The Brazil-born Spain international is expected to play against the Gunners at Stamford Bridge on Sunday, despite niggling hamstring problems.

The 25-year-old has found the back of the net eight times in six league games for the West London outfit.

"I hope he will disadapt on Sunday," Wenger told reporters. "He's done fantastically well. I'm impressed by how well he's done. He's focused, determined and ready for a fight.

"He has players who can find him and the timing of his runs make him a very efficient player."

Meanwhile, Wenger has confirmed that midfielder Aaron Ramsey will be out for three to four weeks with a hamstring injury.