Fernando Alonso confirmed that fractured ribs suffered as a result of a huge crash in Formula One's curtain-raiser in Australia is the reason for his absence at this weekend's Bahrain Grand Prix.
McLaren driver Alonso slammed into the wall and flipped his car several times following a collision with Haas' Esteban Gutierrez, causing the race in Melbourne to be red flagged.
The Spaniard was assessed by FIA doctors on Thursday and it was confirmed Alonso was not passed fit to face.
And Alonso elaborated on his injuries at a news conference, saying: "Last week I was okay on Sunday, some knee pain, but not big things.
"I had the green light from the doctors to leave the track and everything was okay. Monday, I had a little bit of overall pain, but nothing too serious. Then I flew back to Spain and the pain was similar or a little bit more, so we decided to do a check.
"I had a small pneumothorax on the lung, so we took the advice from the doctors to relax at home and make everything come to normal, and we repeated the scan on Monday.
"The pneumothorax is gone but I have some rib fractures, so because of that there is a risk of driving because Formula 1 is a unique sport, a unique position on the car, and G-Forces, so the fracture could move into the lung as well.
"It's not like a broken leg or arm you can deal with the pain, because it's in the chests where there are some organs and we cannot do much more."
Alonso also stated that he is unsure if he will be back in time to race in China on April 17, adding: "It's not 100 per cent. We have another test that I need to do in the next eight or 10 days. After that test the FIA will evaluate again as they did now."
The former Ferrari man missed the opening race of 2015 in Australia following a high speed crash in pre-season testing that left him with reported memory loss, but Alonso played down the risk factor in Formula One.
"We don't think about the risk at any point. You see it now - I have broken ribs, I am here with some pain, it is not easy to sleep sometimes - but I would like to sit in the car and see," he said.
"You understand this is motorsport and anything can happen. You love it so much that it's completely transparent, the risk.
"I've been very lucky all my career. This is my 16th F1 year and it's normal you have accidents here and there. Unfortunately it's happened twice in the last few years that I miss a race."