Alex Waller admits Saints face a 'massive challenge' at Sandy Park on Saturday.
But the prop insists he and his team-mates have the belief that they can claim wins from their final two fixtures in the Aviva Premiership.
After this weekend's game against Exeter Chiefs, Saints must host Harlequins at Franklin's Gardens on the final day.
Jim Mallinder's men currently sit sixth in the Premiership and will guarantee Champions Cup rugby for next season if they do not slip any lower in the standings.
But they will have their work cut out against second-placed Exeter.
"It's a massive challenge," Waller said.
"You see how well Exeter are playing at the minute and they're playing some really good rugby.
"Going down to Sandy Park is always a tough experience and it's not going to be an easy game by any stretch.
"We haven't got an easy last two games so it's going to be a tough ask for us, but the target for us is to win both."
Saints could be home and dry in their pursuit of a Champions Cup place had they managed to convert good performances into wins in recent weeks.
They saw victory snatched away late on in clashes with Leicester, Wasps and Saracens.
And Waller said: "It's been a frustrating couple of weeks, just losing games in the final quarter.
"We're looking to right some wrongs and the target for this week is to play for the full 80 and hopefully come away with a hard-fought victory.
"There is a feeling of frustration when you've come off and things don't go to plan.
"It's no one's fault individually and as a team we can work on seeing out games better.
"It's frustrating for everyone - on the pitch and off the pitch.
"It's not the nicest feeling coming off the pitch, thinking it might be in the bag and then it slips away from everyone.
"It's no one's fault, but it's something we need to work on as a team."
Saints have been able to enjoy plenty of rest in recent weeks with the fact they were eliminated at the Champions Cup pool stages giving them some respite.
"The weeks off have helped," Waller said.
"I've had one or two rests during the season with rotation with my brother and Campo (Campese Ma'afu) so I feel all right.
"It's been a long, old season, a hard season and everything hasn't gone our way so I'm feeling about as good as I do normally at this stage of the season.
"I'm looking forward to a little freshen up in a couple of weeks."
The next two weeks will see Ethan Waller play his final games in Saints colours.
The prop is moving to Worcester Warriors this summer, and Alex admits he will be sad to see his sibling depart.
"I will be sad to see him go," Alex said.
"It's soon becoming a reality. It's coming round quick.
"I am sad to see him leaving and I'm sure a lot of the fans will echo that.
"He's put a lot of time and effort into this club and he does a lot behind the scenes that a lot of people don't see so I'm sorry we're losing him.
"He's made the decision for his career at this time and I'm looking forward to playing against him next year. We've only done that once or twice in our lives so it's going to be interesting."