Lions team doctor James Robson has delivered contrasting medical updates on Wales backs Jamie Roberts and George North ahead of Saturday's first test against Australia in Brisbane.
Centre Roberts limped off during last Saturday's 47-17 victory against the Waratahs, suffering a hamstring strain. Wing North, though, is well on the way back from a hamstring problem. He resumed running yesterday as the Lions completed preparations for their game against the Brumbies in Canberra tonight.
"Jamie is a grave doubt for this weekend, there is no doubt about that," Robson said. "You only had to see how much discomfort he was in at the weekend.
"However, further assessment will be made later in the week as to his availability going forward.
"He has tweaked his hamstring. He has a strain. He got his leg extended, someone came down and flexed his back. It is unfortunate."
North, who on Sunday was rated as "less than 50-50" by Lions head coach Warren Gatland to be available this week, continues to make positive strides.
"An accurate assessment on his availability for selection will take place on Wednesday. At the moment, I think he is doing very well and has a great chance of being fit for this week," Robson said.
"We wouldn't allow him to play if there was any significant risk.
"We will only return him to the coaches for selection if we are confident that medically he is fine."
Gatland says the mid-weekers have everything to play for tonight.
He is fielding his weakest team of the tour in the Lions' final pre-test hit-out, with the entire three-quarter line drafted into the squad as cover for injured backline stars.
Gatland, though, says it's vital the Lions build on the momentum of five straight wins.
"There's no way that we're going out and sacrificing the game. The motivation is there," he said after including 36-year-old international retiree Shane Williams for a shock one-game cameo at Suncorp Stadium.
"I'm sure those guys going out will be incredibly motivated and will want to continue this tour unbeaten.
"But not just that.
"There's still that opportunity for players to put their hand up and say I want to be part of that test XV or that test 23, and that's what that motivation has to be."