Michael Schumacher’s condition has slightly improved but remains critical after he underwent another operation overnight to further reduce pressure on his brain, doctors said on Tuesday.

“He is in a critical condition but it is not the same as yesterday,” Jean-Francois Payen, head of the intensive care unit at Grenoble’s university hospital, where the record Formula One champion is being treated over injuries sustained in a ski accident, told a news conference.

“The situation is better controlled than yesterday. We can’t say he’s out of danger, but we now have a bit more time.” Payen said “the hours to come are crucial for the outcome” and that Schumacher will remain in an induced coma as long as necessary.

“He’s in resuscitation and things change really quickly in a good way and a bad way. We’ve just gained a bit more time.” Schumacher, who won a record seven F1 world titles and retired from the sport for a second time in 2012, fell and hit his head on a rock while skiing off-piste with his son at the Meribel resort on Sunday.

He was transported by helicopter to a hospital in Moutiers before being transferred to a clinic in Grenoble where he underwent a first operation.

Doctors said on Monday that he was in a critical condition but Payen said that a window of opportunity opened later in the day to consider the second operation which lasted around two hours and ended around midnight Monday.

“We had effectively at the end of the afternoon received a transitional improvement on the pressure on the brain. So there is no worsening of the initial lesions. In discussing this with my neurosurgeon colleagues, we decided that since there was an improvement, we should do the operation. We didn’t initially think we would do the operation,” he said.

“It was a relatively good result. So this morning we took some more pictures, some more scans, and we’ve noticed that we’ve evacuated the hematoma further. And so this gives us signs that we have a better controlled situation.” Gerard Saillant, who operated on Schumacher for a broken leg after a crash at the 1999 British Grand Prix and came to Grenoble as “a friend,” said he still has other lesions on the brain that require full medical attention.

“The scans show there are other lessions on the brain, and these lesions need to be kept in check. We need to check on these every hour,” he said.

Doctors said that Schumacher’s family, who have been by his side since Sunday, was constantly informed about their next steps and decisions.

The retired racer’s manager, Sabine Kehm, said Schumacher’s wife Corinna, daughter Gina-Maria and son Mick, were in shock.

“The family is not doing very well, obviously. They are shocked,” Kehm told reporters.

Fans were waiting outside the hospital for news of his health and the outpouring of support for Schumacher on Twitter continued.

“Last day of 2013, we really hope to get some good news from #Schumi very soon,” French Lotus driver Romain Grosjean tweeted shortly before the news conference.

Former US president Bill Clinton also took to Twitter, referring to Schumacher’s support of the Clinton Foundation and other charities.

“Thinking today of Michael Schumacher and grateful for all he’s done,” Clinton said. “My prayers are with him and his family.” Barcelona footballer Cesc Fabregas tweeted: “All the strength for Michael Schumacher. We are all with you.” The German newspaper Bild, meanwhile, reported that Schumacher’s helmet broke in his accident.

“When we arrived at the scene of the accident, his helmet was split,” Bild quoted a rescuer as saying.

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