Canadian scrum-half Morgan Williams, who returned from the Rugby World Cup in Australia last week, has been selected at the expense of Dan Kirton, with the latter droppig down to the bench.
Kafer delayed the team announcement for 24 hours so that he would have an extra day to assess Fiji fly-half Nick Little, who returned from Australia on Thursday, and French back Denis Cech, who joined Saracens on a week's trial from French side Colomiers, after being recommended by Thomas Castaignède.
Both players have been named on the bench for Saturday's clash.
"As I said earlier in the week I was pleased with the win last weekend and equally happy that for the first time in months we didn't see any further injuries," said Kafer.
"We face a tough test on Sunday as London Irish are certainly carrying some form. They're very good technically and don't have any real weaknesses from 1 to 15. We will have to build on what we started last Saturday if we are to contend and the players are well aware of their task."
Saracens: 15 Adryan Winnan, 14 Richard Haughton, 13 Paul Bailey, 12 Ben Johnston, 11 Darragh O'Mahony, 10 Andy Goode, 9 Morgan Williams, 8 Taine Randell, 7 Ben Russell, 6 Tony Roques, 5 Kris Chesney, 4 Simon Raiwalui (captain), 3 Ben Broster, 2 Johnny Marsters, 1 Emiliano Bergamaschi.Replacements – from: Andy Kershaw, Steven Sparks, Stuart Philpott, Ben Skirving, Ryan Peacey, Patrick Phibbs, Dan Kirton, Nicky Little, Denis Cech.