Chelsea manager Jose Mourinho has claimed striker Diego Costa "has a chance" of playing against Swansea on Saturday even though he returned with a hamstring injury from international duty.

The Spanish international went off in the 1-0 defeat to France last week and was pulled out off the squad for the Euro 2016 qualifier against Macedonia.

Mourinho claimed he then returned to West London for treatment and he will assess him during the training session on Friday to decide whether he can feature against Swansea.

"As you know Diego came back inured but that was last Saturday so we had one week to work hard with the medical department and he has a chance to play tomorrow," the manager said.

"We have a training session now to confirm his condition, but he was the only one that came back from the national team with a problem."

Costa has scored four goals in the first three Premier League games while receiving the August Premier League Player of the Month award.

Meanwhile, questioned about Petr Cech's reaction to Thibaut Courtois' new deal, Mourinho said: "I don't think there is a problem.

"Petr is a very intelligent guy, he knows that Courtois is to stay a long time. What happened I think was something that was very much on the table and something that everyone would expect. Now we have Courtois under contact for five years and that's a good situation. I'm more than happy to have both in my team."

Mourinho refused to speak about Manchester United signings Radamel Falcao and Angel Di Maria, but hailed Chelsea's summer transfer business.

"I don't assess them, I just keep saying that I think we did our business well. I think I did well by analysing the situation at the right stage, which was during the last season. My club did an amazing job.

"[Loic] Remy was almost in the last day but that was just consequence of Fernando [Torres]. It was a reaction to an unexpected situation. We did our job in a good way."

The Blues host Swansea hoping to prolong their perfect start to the season after winning each of their first three Premier League games.

Nevertheless, the Welsh club are second in the table as they are the only other Premier League side with a 100% winning record – and the team with the meanest defence so far.

"They had an unexpected result [against Manchester United] for all of us, but they've got nine points, so respect" Mourinho said.

"Every game is a game. The first three matches are not more important than the second group of three and vice versa.

"The next is Swansea, we have nine points, we want 12, 10 at least. We don't change our direction in what we want to do.

"They are a good team with good players. At the end of the season they did not lose an important player. They bought and they bought well. They invested seriously. They did very well to keep good players and bring in players to improve."