London Irish have won just one of their last five games: 23-15 against Gloucester - the only one of those which was played at home.
The Exiles only loss at Madejski Stadium in Aviva Premiership Rugby in their last six games was 12-13 to Bath in round seven.
Northampton Saints have won four of their last five games in Aviva Premiership Rugby, but have lost their last two away games in all competitions - at Bath and Gloucester.
London Irish beat Northampton 14-13 at Franklin's Gardens in round three and have never before achieved a league double over the Saints.
Northampton Director of rugby Jim Mallinder Mallinder says that that accuracy and execution will all have to step up several notches if the Saints positive run is to continue.
"Last Saturday was an important win for us," he said. "As much as you'd like to win with style every week sometimes you have to grind out the result and grabbing your opportunities when you can.
"This is what we did last weekend and although we need the same again in terms of taking our chances we will need to be much better in our all round performance. At times we tried to play too hard last weekend and didn't look after the ball, and we will have to control ourselves more.
"London Irish have a good home record this season, and with some powerful runners out wide like Jonathan Joseph and Sailosi Tagicakibau we will have to be alert defensively.
"They are very organised and as we saw here at Franklin's Gardens in September will play right until the last minute. And in Tom Homer they have one of the best goal kickers in Aviva Premiership Rugby.
"But the spirit in training has been good this week and we are feeling positive ahead of the trip to Reading."
Declan Danaher will return to the London Irish back row and Topsy Ojo returns on the wing with Dan Bowden moving to inside centre.
Adrian Jarvis and Ross Samson form the half back combination. Matt Garvey moves to the second row with Danaher and Hala'ufia returning to the back row alongside Richard Thorpe.
London Irish head coach Toby Booth said: "We were bitterly disappointed with our performance last Saturday and this has given us strong focus for training this week."
"The Premiership table is tight with only six points separating fourth and eighth positions. There is still a lot of rugby to be played and there is still everything to play for."
Match : London Irish v Northampton Saints
Date : Sunday 19th February
Venue :Madejski Stadium
Kick Off : 1.15pm
Live on: Sky Sports
Referee: Andrew Small (66th Premiership game)
15. Delon Armitage; 14. Topsy Ojo; 13. Jonathan Joseph; 12. Daniel Bowden; 11. Sailosi Tagicakibau; 10. Adrian Jarvis; 9. Ross Samson; 1.Max Lahiff; 2. David Paice; 3. Faan Rautenbach; 4. Nick Kennedy (Captain); 5. Matt Garvey; 6. Declan Danaher; 7. Richard Thorpe; 8. Chris Hala'ufia
Replacements: 16. James Buckland; 17. Clarke Dermody; 18. Paulica Ion; 19. Kieran Roche; 20. Jebb Sinclair; 21. Tom Homer; 22. Jonathan Spratt; 23. Darren Allinson
15 Paul Diggin , 14 Vasily Artemyev , 13 George Pisi , 12 James Downey , 11 Noah Cato , 10 Stephen Myler , 9 Martin Roberts , 1 Soane Tonga'Uiha , 2 Andy Long , 3 Paul Doran-Jones , 4 Mark Sorenson , 5 Christian Day , 6 Samu Manoa , 7 Calum Clark (capt) , 8 Roger Wilson
Replacements , 16 Ross McMillan , 17 Alex Waller , 18 Brian Mujati , 19 James Craig , 20 Ben Nutley , 21 Ryan Glynn , 22 Ryan Lamb , 23 Tom May