Saints may have won back-to-back games to put themselves well into contention for a place in the top four going into the LV= Cup break, but Waller acknowledges that the Exiles will be buoyed by last weekend's win over London Wasps and that they cannot be taken lightly.
"We've got a bit of momentum at the moment and hopefully we can get a win to keep that going," the prop told SaintsTV. "Back in September we weren't right mentally when we went to Reading and they punished us. We know that we can't have a single minute off in the Aviva Premiership; every team's a good team and has the capability to beat you.
Jon Fisher will start at number eight for London Irish in the Aviva Premiership match with Northampton at Franklin's Gardens.
Fisher is the only change to the starting side that defeated Wasps at Madejski Stadium last weekend. Setaimata Sa, who arrived at the Club earlier this year, is named as a replacement along with David Paice who has recovered from injury.
"Northampton have got a few wins under their belt in recent weeks and are playing some good rugby," said Irish boss Brian Smith.
"It is always a physical challenge against Northampton and I envisage tomorrow being no exception. The squad is looking forward to the challenge."
Meanwhile, Dylan Hartley will captain Northampton following his release from the England camp, with Courtney Lawes and Ben Foden also included in the starting XV. Samu Manoa moves to blindside flanker.
Tom May starts at inside centre alongside George Pisi, with rising star Jamie Elliott on the left wing. Stephen Myler gets the nod at fly-half ahead of Ryan Lamb.
"We can't switch off and we've been preparing for London Irish in the same way we do for every game," said Northampton prop Alex Waller.
"They're a good team with good forwards and some exciting backs, and now the ground's firming up that's when they could come into play.
"We're going to have to go into this game focused and not look at the table in terms of where they are. We need to switch on and be in the same frame of mind we were last week."
Form: Saints have won three of their last four Aviva Premiership matches ahead of the Irish's visit but have won only two of their last five fixtures at Franklin's Gardens in the tournament. Irish arrive not only buoyed by beating London Wasps 30-19 last time out for a third win in their last four Aviva Premiership matches, but also by the fact that they got the better of their hosts 39-17 in the reverse fixture in round six. However the Exiles have never before achieved a league double over the Saints.
Northampton: 15 Ben Foden, 14 James Wilson, 13 George Pisi, 12 Tom May, 11 Jamie Elliott, 10 Stephen Myler, 9 Lee Dickson,8 GJ van Velze, 7 Phil Dowson, 6 Samu Manoa, 5 Mark Sorenson, 4 Courtney Lawes, 3 Tom Mercey, 2 Dylan Hartley (c), 1 Soane Tomga'uiha.
Replacements: 16 Ross McMillan, 17 Alex Waller, 18 Brian Mujati, 19 Mark Sorenson, 20 Ben Nutley, 21 Martin Roberts, 22 Ryan Lamb, 23 Dom Waldouck.
London Irish: 15 Tom Homer, 14 Topsy Ojo, 13 Guy Armitage, 12 Shane Geraghty, 11 Marland Yarde, 10 Ian Humphreys, 9 Pat Phibbs, 8 Jon Fisher, 7 Ofisa Treviranus, 6 Matt Garvey, 5 Bryn Evans (c), 4 George Skivington, 3 Halani Aulika, 2 Scott Lawson, 1 Max Lahiff.
Replacements: 16 David Paice, 17 Jerry Yanuyanutawa, 18 Leo Halavatau, 19 Kieran Low, 20 Jebb Sinclair, 21 Sailosi Tagicakibau, 22 Setaimata Sa, 23 Jack Moates.
Date: Saturday, March 2
Venue: Franklin's Gardens
Referee: JP Doyle
Assistant referees: Gareth Copsey, Nigel Carrick