Fernando Alonso says that rib fractures which he suffered during the Australian Grand Prix would pose too great a risk to allow him to participate in Bahrain this weekend.
Alonso's McLaren clipped the back of Esteban Gutierrez at Albert Park and careered into the wall, before being tipped into a roll, eventually landing upside down.
Alonso was diagnosed with a small pneumothorax on the lung and while that has cleared, rib fractures mean that doctors have ruled him out of competition at Sakhir.
"To summarise a little, last week I was okay Sunday - some knee pain but not big things. I had the green light to leave the track and everything was okay," Alonso said on Thursday.
On Monday I had a bit of overall pain, nothing too serious. Then I flew back, arrived in Spain and the pain was a little more, so we did a proper check and I had a small pneumothorax on the lung.
"We took advice from the doctors to relax at home and repeat the scan last Monday - the pneumothorax is gone more or less but I had some rib fractures.
"And because F1 is a very unique position in the car, and with the g-forces, there was a risk the fractures could move into the lung.
"It’s not like broken leg or arm where you can deal with the pain; it’s the chest where there are organs, so we cannot do much more."
Alonso was hesitant to confirm that he will be able to return to action in China.
"It is not 100 percent - it will be another test I need to do in the next eight or 10 days and after that the FIA will evaluate again, as they did today," he added.
Alonso will be replaced at McLaren by reigning GP2 champion Stoffel Vandoorne.