Paul Diggin's recent good form means Ashton has been left out as Bruce Reihana returns to full-back after being rested against Bristol last week.
Euan Murray, Roger Wilson, James Downey, Ignacio Fernandez Lobbe and Lee Dickson all return to the s
tarting line-up with Carlos Spencer continuing on the bench. The Kiwi will make his 100th appearance for the club if he comes on.
Director of rugby Mallinder says that the Northampton Saints team will have to be at their very best on Saturday afternoon to overcome high-flying Harlequins.
The Saints are unbeaten at Franklin's Gardens this season, but face high-flying Harlequins as the Guinness Premiership resumes this weekend. The past two weekends saw Quins complete a double over Stade Francais and Mallinder has prepared for a stern contest.
"Harlequins are one of the form sides in Europe at the moment," he said today. "Dean Richards has put together a squad full of talented players who have become a cohesive team. They like to play with the ball in hand but the games against Stade Francais showed how much they can impose control on a match too.
"However we are confident going into tomorrow's match. Everyone who played in the Challenge Cup games against Bristol put in good performances and there has been plenty of competition for the 22 places in the squad for Saturday. We have a home record we are proud of and will be working hard for a good result against Harlequins."
NORTHAMPTON SAINTS TEAM TO PLAY HARLEQUINS:Guinness Premiership Round 9
Franklin's Gardens
Saturday, December 20
Kick off 3pm
15 Bruce Reihana (capt)
14 Paul Diggin
13 Jon Clarke
12 James Downey
11 Sean Lamont
10 Stephen Myler
9 Lee Dickson
1 Soane Tonga'uiha
2 Dylan Hartley
3 Euan Murray
4 Ignacio Fernandez Lobbe
5 Christian Day
6 Mark Easter
7 Scott Gray
8 Roger Wilson
Replacements
16 Paul Shields
17 Tom Smith
18 Alex Rae
19 Mark Hopley
20 Ben Foden
21 Carlos Spencer
22 Chris Mayor
Tickets are still available for Saints v Harlequins. Prices start from just £13 for juniors and concessions and £22 for adults. Book by calling the Saints Ticket Office on 01604 581000 or order online via the Saints' official website -
www.northamptonsaints.co.uk