Deacon joins Martin Castrogiovanni as the two changes made by director of rugby Richard Cockerill following the win over Sale.
George Skivington and Dan Cole are the players to make way, with both named on the bench.
The Tigers are without Ben Youngs, Manu Tuilagi, Mathew Tait, Anthony Allen and Billy Twelvetrees for the encounter due to injury, while scrum-half Micky Young is still working his way back from a calf problem.
The Exiles have named World Cup trio of Alex Corbisiero, Sailosi Tagicakibau and Jebb Sinclair in their line-up for the trip to Welford Road.
Canada forward Sinclair starts his first game for the club at No.8, while Corbisiero and Tagicakibau come in at prop and on the wing respectively.
Head coach Toby Booth has also made three further changes with scrum-half Ross Samson, second row James Sandford and centre Steve Shingler handed starts.
As a result Max Lahiff, Richard Thorpe and Darren Allinson drop to the bench, while Jonathan Joseph, Nick Kennedy and Delon Armitage are missing from the match-day squad.
Leicester Tigers: 15 Geordan Murphy (c), 14 Scott Hamilton, 13 Horacio Agulla, 12 Matt Smith, 11 Alesana Tuilagi, 10 Toby Flood, 9 Sam Harrison, 8 Thomas Waldrom, 7 Julian Salvi, 6 Tom Croft, 5 Geoff Parling, 4 Louis Deacon, 3 Martin Castrogiovanni, 2 George Chuter, 1 Marcos Ayerza.Replacements: 16 Tom Youngs, 17 Boris Stankovich, 18 Dan Cole, 19 George Skivington, 20 Ed Slater, 21 James Grindal, 22 Jeremy Staunton, 23 Niall Morris.
London Irish: 15 Tom Homer, 14 Topsy Ojo, 13 Steven Shingler, 12 Shontayne Hape, 11 Sailosi Tagicakibau, 10 Dan Bowden (c), 9 Ross Samson, 8 Jebb Sinclair, 7 Jamie Gibson, 6 Declan Danaher, 5 Bryn Evans, 4 James Sandford, 3 Paulica Ion, 2 David Paice, 1 Alex Corbisiero. Replacements: 16 James Buckland, 17 Max Lahiff, 18 Faan Rautenbach, 19 Matt Garvey, 20 Richard Thorpe, 21 Adam Thompstone, 22 Adrian Jarvis, 23 Darren Allinson.
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