For Shannon hooker Flannery, the game will mark his first start in a green jersey and in the 6 Nations proper. For Garryowen back row Wallace, it's the chance of a 23rd cap and his first 6 Nations start since the 37-16 win over Scotland in March 2004 that confirmed Ireland's Triple Crown-winning season.
When asked about his selection, Ireland coach Eddie O'Sullivan said afterwards: "The hooking position was a tight call between Jerry and Rory (Best). When we picked the team in the autumn, Jerry was on the bench for Munster. But then Frankie Sheahan got injured and Jerry started playing for Munster. He came off the bench against Romania and has had a really good run of form since.
"He's edged Rory with his performances in the Heineken Cup. He's our form hooker at the moment."
Praising Wallace's work rate, O'Sullivan added: "David has played particularly well in the last month and has forced his way into a very difficult department of the team.
"Back in the autumn he didn't get into the squad because he wasn't in the Munster team. His first Heineken Cup game was after the autumn squad was picked and since then he's got better and better. He'd been dogged by injury and his form wasn't great earlier in the year. Ball carrying has always been a strength of David's game.
"But there are other important aspects to playing back row, such as being involved at the breakdown and linking up with the back line and he's improved in these areas.
"His work rate has gone up dramatically - against Sale a couple of weeks ago he had six poaches which is a colossal amount of work on the opposition's ball. This was an area he hadn't focussed on before. We talked to him at length about it and he's worked on it."
Gordon D'Arcy flicks a pass away as squad newcomer Eoin Reddan (left) of Wasps and returning team captain Brian O'Driscoll (right) watch on.
Jerry Flannery and David Wallace hold court underneath the Guinness East Stand at Lansdowne Road. Training on Tuesday was switched to the back pitch at Lansdowne Road due to adverse weather conditions at last week's training base of St. Gerard's School in Bray, County Wicklow.
The players take on refreshments beside the back pitch at headquarters.
The all-Munster front row of Marcus Horan, Jerry Flannery and John Hayes (right), which will feature for Ireland against Italy from kick-off on Saturday, gets set for some scrum practice.
Brian O'Driscoll practices his line-kicking on the back pitch. O'Driscoll said at Tuesday's press conference, when asked about his injury lay-off for a dislocated shoulder: "I don't think I was ever worried, but there were moments of frustration when I couldn't see an end to it all -moments when I couldn't see when the injury was going to heal completely.
"There were some frustrating times when I didn't have the movement in it that I used to, but the closer I got to the point of playing, the more confident I felt. And after playing games, my confidence continued to improve.
"Even now, I'm not exactly where I want to be at. It's improving all the time but I feel that I perhaps have 5-10% more in it."
A 'relaxed' Denis Leamy with his Munster and Ireland team mate Jerry Flannery after Tuesday's training session.
Join the Irish Rugby Supporters Club, in association with Canterbury of New Zealand - meet the players, exclusive access, competitions, tickets and much more. To join click here
**All photos by Billy Stickland of Inpho Photography**