Jonny Wilkinson is unlikely to play in Newcastle's Heineken Cup quarter-final against Stade Francais, according to the Falcons fitness coach.
Steve Black said it would also be a "huge ask" for Wales flanker Colin Charvis to be fit in time.
Black said: "We'll not try to press the fast forward button even though this game's very important. Jonny and Colin will come back when they're ready."
Wilkinson suffered a recurrence of a knee injury just over three weeks ago.
"It is all going very well and I am very pleased, but whether he will be
ready for the game in Paris on Saturday is a big ask, it really is," Black said.
There is better news in the front row, with Ian Peel, Micky Ward, James Isaacson and Galo Quinones on course to make the trip to France.