Fernando Alonso will miss next week's season-opening Australian Formula One Grand Prix on doctors' advice after a heavy crash in testing, the Spaniard's McLaren team said on Tuesday.
"Fernando has understood and accepted that advice, and the two McLaren-Honda cars will therefore be driven in Australia by Fernando's team-mate Jenson Button and the team's test and reserve driver Kevin Magnussen," they said in a statement.
Australia would have marked a new start for Alonso at McLaren, who are also embarking on a new engine partnership with Honda, after five years at Ferrari.
However, the Spaniard spent three nights in hospital last week after losing control and hitting the wall in testing in Barcelona on Feb. 22.
McLaren said the 33-year-old had undergone more tests on Monday evening and been given the all-clear.
"However, Fernando's doctors have recommended to him that...for the time being he should seek to limit as far as is possible any environmental risk factors that could potentially result in his sustaining another concussion so soon after his previous one," they added.
"In order to limit those environmental risk factors, specifically, his doctors have advised that he should not compete in the imminent Australian Grand Prix meeting."
First practice for the March 15 race in Melbourne starts on Friday, March 13.
Denmark's Magnussen raced for McLaren last season, finishing second in Australia after local hero Daniel Ricciardo was disqualified for Red Bull.
The chances of him returning to the podium look remote this time around, with McLaren struggling in testing to get laps under their belt due to persistent troubles with the new V6 turbo hybrid engine.
Alonso has not missed a race since the 2005 U.S. Grand Prix, which was boycotted for safety reasons by drivers whose cars were equipped with Michelin tyres after problems emerged in practice.
McLaren said the doctors had recognised that the double world champion felt fit and well, and considered himself ready to race.
"They are comfortable with the fact that he has already recommenced physical training, with a view to preparing for a return to the cockpit of his McLaren-Honda car for the Malaysian Grand Prix meeting on March 27th, 28th and 29th," the team said.
"Indeed, his doctors are supportive of that ambition, satisfied as they are that he sustained no damage whatsoever during his testing accident."