Australia opener David Warner underwent a thorough fitness test on Thursday after concerns that an upper-leg injury might rule him out of the World Cup opener against Afghanistan this weekend.

The 32-year-old missed the defending champions' final warm-up match against Sri Lanka on Monday and was unable to train on Wednesday despite his desire to make his return to international cricket in Bristol on Saturday.

Warner, who scored 345 runs at an average of 49.28 in Australia's run to the title four years ago, returned to the national set-up last month after serving a one-year ban for his part in the Newlands ball-tampering scandal.

"He is desperate to play, he'd love to play like all 15 players would," Australia's coach Justin Langer told reporters before Thursday's training session. "He was a bit sore on Wednesday. He's just a bit sore in his right glute. We'll have a pretty good idea today, how he moves and how he pulls up in the morning."

If Warner is unable to take his place in the side, it would resolve at least one selection headache for Langer when he comes to naming his top order.

Batsman Usman Khawaja opened with skipper Aaron Finch and scored a bright 89 in Monday's warm-up win over Sri Lanka to stake a claim for a place at the top of the batting order.

Langer said Warner would open he if was cleared to play but it was important to be fair to other players by making a reasonably early call on his fitness.

"We don't want to be getting to Saturday morning and making a call, when a couple of other guys are wondering if they are going to play or not going to play," he added. "The earlier we can make the decision, the better. Hopefully we can make it (Thursday night) where he says 'yep, I'm ready to go', or 'I'm not sure' if he pulls up sore in the morning."

Australia humiliated Afghanistan in Perth at the 2015 World Cup by hammering a tournament record 417 for six on their way to a record 275-run victory. Langer, however, said the Afghans had some top quality players and there would be no room for complacency.

"We will show them great respect because we do have respect for what they are doing," he said.