Wilkinson has been out with a knee injury since September
Newcastle director of rugby Steve Bates has delivered a gloomy prognosis on Jonny Wilkinson's chances of being fit to make this summer's Lions tour.
Wilkinson has been unable to complete a full week's training since dislocating his knee in September.
"Time is running out for him to get back on the field," said Bates.
"We've got two more games this season and there's no guarantee he will play in either. If I was the Lions coach I'd be concerned about that lack of rugby."
British and Irish Lions head coach Ian McGeechan will name the squad he will take to world champions South Africa on 21 April, but Bates suggested the tour might prove too tough an environment for a player who has played no rugby for eight months.
"We're still working hard to try and rehabilitate that knee and make sure that things are progressing," said Bates, speaking after Newcastle's 32-13 European Challenge Cup quarter-final defeat at Saracens.
"The difficulty is this Lions trip is going to be really hard and physical.
"If you are not absolutely on your game you are going to get exposed in South Africa.
"He's a class player and you've got to take that into consideration but the poor guy hasn't played since September.
"It would be tough then to ask him to go and play against the South Africans in full flow."
Wilkinson has suffered a series of injuries since the 2003 World Cup and has undergone two knee operations.