Saints will be without Alex Mitchell for the start of the season, with boss Chris Boyd revealing the scrum-half has suffered 'a fairly major injury'.
Mitchell tore his patellar tendon during an impressive display for an England XV against the Barbarians at Twickenham on June 2.
And the talented 22-year-old, who was Saints' young player of the season for the 2018/19 campaign, is now set to be ruled out until November.
Saints start their season with a Premiership Rugby Cup game at Sale Sharks on September 21.
Their first league game comes at Saracens on October 19.
And Boyd said: "It's tough for Alex because he suffered a fairly major injury in that England game.
"He tore a patellar tendon in his knee and he would be looking to be back around round five or six of the Premiership.
"Perhaps he could be back for the first block in Europe so he's not too far away."
When asked for an update on the rest of the squad, Boyd said: "Everyone's got a chance of playing in the first Premiership game, with the exception of him (Mitchell).
"I don't think he'll be ready to start the season, but everyone else could be.
"The three guys who had ACL injuries last season - Harry Mallinder, Mikey Haywood and Andy Symons - should all be back during the PRC block at the start of the season.
"Reece Marshall had a fairly nasty hamstring tear so he may not be ready for the start of the season.
"Dylan (Hartley) is a bit unknown but he probably ran the best I've seen him run for six months yesterday (Monday) and we're not going to put a time-frame on Dylan.
"When he's ready he'll play, if he's not he won't.
"We've got a few long-termers who are just getting to the end of their rehab so it's not looking too bad at this stage."
On Hartley, who has not played since the win at Worcester Warriors last December due to a knee problem, Boyd added: "He's done all the unit work - all the scrum, lineout, mauling work.
"His running load is modified and what he does is modified but he's certainly around the club.
"I spoke to him earlier and he's done some fantastic work with the younger guys.
"I'm not asking him to coach by any means, but he's got a lot of knowledge and he's happy to impart that to the guys in the Academy and the young guys in the environment.
"He's been great but at the end of the day all I want for him is to get happy, healthy and frisky, and when he's ready to play he'll play."
With World Cup call-ups for the likes of Courtney Lawes, Lewis Ludlam, Piers Francis, Api Ratuniyarawa and Dan Biggar, Saints could find their squad stretched.
But Boyd said: "It's getting pretty thin in some places but the nice thing is that if we have faith and confidence in the young guys we might end up in some pretty crucial games with some pretty young guys on the field.
"We're certainly not ready to push the panic button at this stage and we've got a lot of faith and trust in those young guys because they've worked hard.
"We'll resist pulling in too many replacements."