Jim Evans comes in for the injured Simon Miall – who is out for six months with a knee injury – in the second row, with Roy Winters prodiving cover from the bench, while in the front row, Ceri Jones starts at loosehead prop. Mike Worsley will start from the bench.
Hooker Ace Tiatia, who will appear before a Rugby Football Union (RFU) disciplinary panel at Twickenham on Monday for a dangerous tackle on London Irish centre Nick Greenstock, has been named in the starting line-up.
"We will face a very stern test at Vicarage Road on Sunday," said Quins Chief Executive, Mark Evans.
"Saracens are playing some very good rugby at the moment having won away at Newcastle and drawn against Leicester in their last home game. Every Zurich Premiership game is a tough assignment and we expect Sunday to be the same."
NEC Harlequins: 15 Gavin Duffy, 14 Rob Jewell, 13 Josh Taumalolo, 12 Mel Deane, 11 Ugo Monye, 10 Paul Burke, 9 Ben Willis, 8 Tony Diprose, 7 André Vos, 6 Pat Sanderson, 5 Jim Evans, 4 Bill Davison, 3 Jon Dawson, 2 Ace Tiatia, 1 Ceri Jones.Replacements: 16 Tani Fuga, 17 Mike Worsley, 18 Laurent Gomez, 19 Roy Winters, 20 Luke Sherriff, 21 Simon Keogh, 22 Andy Dunne.
Kick-off: 15.00 BST (14.00 GMT)