Tighthead prop Castrogiovanni and lock Deacon have made only one appearance each as a replacement since returning from Rugby World Cup duty, but are ready to return to the Tigers team at Welford Road this weekend.
Castrogiovanni comes into the front row as Dan Cole, starter in each of the two games since his return to the club, switches to a place among the replacements, and Deacon comes into the second row, with George Skivington on the bench.
Director of rugby Richard Cockerill said: “We had a good win at Sale last week but it is just one game and we know we have to build on that.
“We have to be looking for a more complete performance moving on from here because we made some errors at Sale, especially in the first half.
“London Irish score plenty of tries, as we saw here last year, and they are a very dangerous team.”
Ben Youngs, Manu Tuilagi, Mathew Tait, Anthony Allen and Billy Twelvetrees are unavailable due to injury and scrum-half Micky Young played an hour of Monday’s Development XV match as he works his way back from a calf problem.
Tigers will be supporting the Royal British Legion Poppy Appeal at Saturday's game and collectors will be stationed throiughout the stadium. There will be a minute's silence before kick-off.
The Aviva Village with inflatables and games is open outside the Caterpillar Stand before the game, and the Junior Tigers Club - including the Crusha milkshake bar - is open in Final Whistle from 1.05pm.
The club will be staging a musical fireworks display on the pitch 10 minutes after the final whistle.
Match tickets are available now. Phone the Tigers ticket office on 0844 856 1880, call in at Welford Road (open 8.30am-5pm Friday and from 9am Saturday) or book online and collect from the collection point outside the Caterpillar Stand on the way to the game.
Leicester Tigers (v London Irish, Aviva Premiership, Welford Road, Saturday 3.05pm)
15 Geordan Murphy (c)
14 Scott Hamilton
13 Horacio Agulla
12 Matt Smith
11 Alesana Tuilagi
10 Toby Flood
9 Sam Harrison
1 Marcos Ayerza
2 George Chuter
3 Martin Castrogiovanni
4 Louis Deacon
5 Geoff Parling
6 Tom Croft
7 Julian Salvi
8 Thomas Waldrom
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’s World Cup trio of Alex Corbisiero, Sailosi Tagicakibau and Jebb Sinclair are called into the starting line-up for the Exiles.
Sinclair starts his first game for the club at No8, while Corbisiero and Tagicakibau start their first games of the season.
Head coach Toby Booth said: "We've been competitive at Leicester under my tenure, but have never won. It's a very tough place to go. We're up for it as there is another Premiership four points up for offer.”
London Irish: 15 Tom Homer; 14 Topsy Ojo; 13 Steven Shingler; 12 Shontayne Hape; 11 Sailosi Tagicakibau;10 Dan Bowden (c); 9 Ross Samson; 1 Alex Corbisiero; 2 David Paice; 3 Paulica Ion; 4 James Sandford; 5 Bryn Evans; 6 Declan Danaher; 7 Jamie Gibson; 8 Jebb Sinclair
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