Dylan Hartley will be given every opportunity to prove he is ready to make his comeback against Exeter on Saturday but Northampton will not gamble on his fitness with the World Cup looming.
Hartley has been out since December because of a knee problem and his involvement in the Gallagher Premiership play-off at Sandy Park is far from certain despite recent medical bulletins stating he is on the brink of a return.
The 33-year-old hooker was one of Eddie Jones' co-captains alongside Owen Farrell until injury struck and will be named in England's training squad for Japan 2019.
Northampton are mindful of the potential damage caused by a premature return to action and will not take any risks even though they face their biggest match of the season against Exeter.
"As the curve of his recovery has been pretty undulating, there is an element that we don't want to put him back in when he's not quite right. We'll give him until the 11th hour," Saints assistant coach Phil Dowson said.
"He's pretty philosophical about it. He's old now. He's bright enough, knows his body well enough and he's played enough rugby to know that if he pushes it now then he misses an obvious opportunity down the track.
"But at the same time he wants to be involved in the first semi-final for quite some time. Dylan has the final say because he knows how he feels."
Northampton are facing an all-too familiar crisis at hooker as Mike Haywood is also out with a knee injury, while Reece Marshall is a doubt because of a hamstring injury incurred in last Saturday's rout by Exeter.
James Fish is an option and Darren Dawidiuk has been brought in on loan from Coventry as emergency cover for the third time this season.
"Dylan trained twice last week and has done bits and pieces this week. It's about how we manage his recovery," Dowson said.
"We have to taper it off and then build it up again. It's whether this game comes too soon for him. What we don't want to do is play him this week and then he has another long lay-off.
"We've got somebody prepped up to cover it off if we need, but we're keeping all options open. Dylan and Reece are both experienced enough in how we play to be able to pick up the pieces."