At fly-half Eoghan Hickey takes over from the injured Mike Catt, while in the front row Tonga Leaaetoa starts at loose-head prop in place of Alex Corbisiero who is named among the replacements.
Elvis Sevialii, who joined from Sale Sharks last month, is named as a backs replacement and lock forward Nick Rouse is also named in a Guinness Premiership matchday squad for the first time.
Paul Hodgson captains the team in the absence of Bob Casey who is injured.
Having played one of last seasons Guinness Premiership finalists last week, we have to play the other tomorrow, said Toby Booth, London Irish head coach.
If you want to rank among the best in the country then you have to play the best and Leicester Tigers have proved that time and again.
Our campaign got off to a good start last Saturday. The players performed well on a big stage and have every right to be pleased with their performance. However, there is no time to enjoy the victory as we face an equally stern test tomorrow.
London Irish (v Leicester Tigers, Welford, Saturday 3pm)
15 Peter Hewat
14 Topsy Ojo
13 Delon Armitage
12 Seilala Mapusua
11 Sailosi Tagicakibau
10 Eoghan Hickey
9 Paul Hodgson (captain)
1 Tonga Leaaetoa
2 Danie Coetzee
3 Faan Rautenbach
4 Nick Kennedy
5 Gary Johnson
6 Richard Thorpe
7 Steffon Armitage
8 Chris HalaUfia
Replacements: 16 Alex Corbisiero, 17 David Paice, 18 Nick Rouse, 19 Declan Danaher, 20 Jonathon Fisher, 21 Peter Richards, 22 Elvis Sevialii