text: Diego Costa will miss four weeks with a hamstring injury, Chelsea manager Jose Mourinho has confirmed. The Spain striker aggravated a hamstring problem in last weekend's win over Stoke. Costa was already certain to miss the games against Queens Park Rangers and Manchester United but had hoped to return in time for the clash against Arsenal on April 26. Diego Costa (centre) has been ruled out for up to the next four weeks after injuring his hamstring vs Stoke . Costa limped off just 11 minutes into his return from injury in Chelsea's 2-1 win over Stoke City on Saturday . The 26-year-old (right) lays on the Stamford Bridge turf in a heap after damaging his hamstring again . But Mourinho says Costa will be fit enough to face the final four games of the season, starting with the clash against Crystal Palace on May 3. 'Only Diego is injured, everybody else is fine and ready,' Mourinho said during the club's pre-match press conference on Friday. '[John Obi] Mikel is ready. [Cesc] Fabregas with a mask, but ready too. No problems. 'We have eight matches to play, if he [Costa] plays four it's normal,' Mourinho said. 'If he plays three it's a little bit below what I'm expecting. If he plays five it's more than I'm expecting.' Costa has a history of hamstring problems but Mourinho is refusing to let his focus shift from Sunday's game at Loftus Road. Asked whether he was concerned about the former Atletico Madrid forward's latest injury, the Chelsea boss said: 'Not concerned. I'm concerned about the match on Sunday. 'At this moment I don't want to think of him (Costa) for two, three weeks.' Blues boss Jose Mourinho (left) hopes to have Costa back for their final four games of the season .
target: Chelsea beat Stoke 2-1 at home in the Premier League on April 4 .
  Diego Costa limped off in the second half after aggravating his hamstring .
  Blues travel to QPR on Sunday in a west London derby at Loftus Road .