Jim Mallinder says Saints’ international stars are not assured of starts.
And the director of rugby has hailed the way his players have stepped up in the absence of key men such as Dylan Hartley and George North.
Hartley, who skippered England to the Grand Slam, and Wales wing North, who has been shortlisted for the Six Nations player of the tournament prize, have impressed for their respective countries.
They have returned to Franklin’s Gardens this week ahead of Sunday’s game against Harlequins.
Hartley is being assessed after the head injury he sustained against France, while North will hope to start against Quins.
Kieran Brookes is also back at the club, while Courtney Lawes is closing in on a return to full fitness following the ankle injury he sustained at Saracens on March 5.
And Mallinder said: “We’ve got our international lads who will be back this week so hopefully they’re all fit.
“We just need to think about what we need to do in terms of our strategy to get them back playing.
“Courtney Lawes has been back with us now for a couple of weeks and we just need to get him match fit and playing.
“I’m very pleased with the performances of the squad members and they’ve put pressure on those internationals. They’re not going to walk in just like that.”