The Saints missed out on lifting the LV= Cup last Sunday, and with the league table as close as ever with just five games to play, Mallinder said that the team had to use the Sixways disappointment as motivation to secure an Aviva Premiership play-off spot.
"The dressing room was a quiet place after last Sunday's game, but I've been pleased with the reaction in training this week," he said ahead of the visit of Dai Young's side to Franklin's Gardens (kick-off 5.45pm).
"The attitude has been very positive and everyone has put in plenty of effort to try and get a place in the team.
"Over the past few weeks, the whole squad has played well, and with the internationals coming back selection decisions have been difficult. So everyone in the 23-man squad deserves their place and we are looking for a good performance tomorrow evening.
"Wasps will be tough opponents for us. Like ourselves they are fighting for every league point and it will be a challenging game."
England quartet Ben Foden, Chris Ashton, Lee Dickson and Phil Dowson return for Saints, with scrum-half Dickson skippering the side.
Club captain Dylan Hartley cannot play pending a Six Nations disciplinary hearing next Tuesday, while Saints have suspended flanker Calum Clark as he prepares to face Rugby Football Union disciplinary chiefs on Monday.
Meanwhile, Wasps director of rugby Young has stuck with Hugo Southwell as captain from full-back, after he successfully led the team to a win against London Irish in their last outing.
Richard Haughton has recovered from the injury that kept him out of that game, and takes his place out wide, while Jack Wallace keeps his spot on the other wing.
Dom Waldouck and Elliot Daly make up a familiar pairing in the centres, while Nick Robinson orchestrates from 10 and Nic Berry starts at scrum-half.
In the front-row, Tom Lindsay starts at hooker, flanked by the usual partnership of Tim Payne and Ben Broster.
James Cannon and Richard Birkett retain their places in the second-row, as do the back-row trio of Joe Launchbury, Jonathan Poff and Sam Jones.
On the bench, club captain John Hart returns from a lengthy injury to take his place amongst the replacements.
"Having lost out to Leicester in the final of the LV=Cup last weekend, I am sure that Northampton will come at us with a lot of firepower this weekend, wanting to cement their place in the top four," said Young.
"We are aware of the threat that Northampton pose, especially at Franklin's Gardens, and we know that we must be firing on all cylinders this weekend if we want to get a result."
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