Croatia captain Niko Kovac is expected to recover from a rib injury in time to play in Sunday's Group F clash against Japan.

The midfielder had to leave the field after 40 minutes of the 1-0 defeat against Brazil after tangling with Ze Roberto.

He returned to training on Thursday morning and even though he could only complete 15 minutes of the session, team doctor Zoran Bahtijarevic took that as a positive sign.

"Niko Kovac had treatment and feels much better, although he is still in pain. I'm optimistic he will play," said Bahtijarevic.

Striker Ivica Olic has responded well to treatment on the thigh injury he picked up against Brazil and should be fit to play against Japan and in the potentially crucial game against Australia next Thursday.