Fernando Alonso has admitted his participation at this week's Chinese Grand Prix remains in doubt.
The Spaniard, who sustained fractured ribs following his huge crash at the Australian Grand Prix in March, was sidelined for the last race in Bahrain after he failed an FIA medical test.
Alonso will undergo further scans by the sport's governing body on Thursday to determine whether he will be fit to race in Shanghai.
"It was disappointing to be told I couldn't race in Bahrain, but I fully respected the decision of the FIA medical team," said Alonso.
"While I hope I'll be back in the cockpit on Friday, until I get the all-clear from the doctors to race - whenever that may be - we cannot assume anything, but I'm continuing to prepare for the race weekend as normal."
Alonso has updated his fans on social media with his progress since Bahrain, posting pictures of himself in training and one of him using a bone-healing ultrasound system on his injured ribs.
He was replaced in Bahrain by Stoffel Vandoorne, McLaren's reserve driver, who out-qualified Jenson Button before scoring the team's first point of the season after he crossed the line in 10th.
Alonso continued: "Stoffel did a great job in Bahrain and although Jenson suffered reliability issues, it was positive to see that both cars ran quite strongly during the weekend.
"It was also interesting for me to see the race weekend unfold from a different perspective, which helped me to understand everything that goes into getting the cars on track and learn a lot about the different processes, although I'd still prefer to be racing.
"I've always enjoyed driving in China - I've won there twice before - and I hope we'll be able to have some good battles on track and see more progress this weekend."
Vandoorne is on standby to race again in Shanghai should Alonso be unable to return.