Stoffel Vandoorne is "on standby" should FIA doctors once again sideline Fernando Alonso in China, McLaren-Honda have confirmed.
Alonso sat out the Bahrain Grand Prix recently with chest injuries, but travelled to China early this week in a bid to be cleared fit to return.
He said on Tuesday: "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."
Team boss Eric Boullier said: "Once again, Stoffel will be on standby until Fernando has his routine meeting with FIA doctors on Thursday, and until then we will be readying ourselves as normal."
Teammate Jenson Button, meanwhile, will have the second of his five engines for the 2016 season fitted to his car in China, following his failure in Bahrain.
