Jonny Wilkinson has been given no better than a "50-50" chance of making his latest comeback in Saturday's European Cup clash between Newcastle and Stade Francais.
The England captain and British & Irish Lions fly-half will travel to Paris with his Falcons colleagues, having been named among 11 possible replacements by Newcastle boss Rob Andrew.
Andrew intends confirming the final seven-strong bench contingent - subject to fitness tests - on Saturday morning, with Wilkinson and Wales flanker Colin Charvis among those hoping for selection.
Both players - Wilkinson (knee) and Charvis (foot) - missed the entire Six Nations Championship through injuries.
Fly-half Wilkinson returned from a knee ligament problem in Newcastle's Zurich Premiership defeat against Harlequins almost three weeks ago, but he lasted just 34 minutes before hurting his left knee again after tackling Quins prop Ceri Jones.
Wilkinson has not played Test rugby since the World Cup final 16 months ago due to shoulder/neck, knee and bicep injuries.
"Jonny is no more than 50-50 at the moment," said Andrew.
"He has done part of our training this week, but hasn't done some of it, and we will have to wait until the day of the game to decide on him.
"Colin Charvis is in the same boat, and (prop) Ian Peel is even less than 50-50. We will have a look at all of them nearer the game, but we won't take any risks if they are not ready."
Newcastle's league appointment with Worcester on Sunday week could prove a more realistic target for Wilkinson. The game is scheduled just 24 hours before Sir Clive Woodward announces his Lions squad to tour New Zealand this summer.
In the absence of co-captains Wilkinson and Peel, England centre Jamie Noon will skipper Newcastle on their daunting Parc des Princes mission.