The 29-year-old Stoke player will bring up his half-century at Cardiff City Stadium in a game which has been largely overshadowed by the focus on whether Gareth Bale would play for Wales, and whether he will leave Tottenham for Real Madrid.
Whelan, first capped back in 2008, may not possess the sort of star quality that the home side will be missing as Bale nurses a foot injury, but skipper O'Shea has described him as the sort of player his team-mates are delighted to have on their side.
Sunderland defender O'Shea said: "Glenn has been around the squad for a while and he has been doing his stuff for Stoke in the Premier League.
"His 50 caps has come around quick and he is one of the unsung heroes who gets glossed over, but the players appreciate him when we go into tough battles in European games.
"You know exactly what you get with Glenn, he is able to do more than mix it, he can produce brilliant moments passing and shooting.
"He is a valuable member of the squad, hopefully it will go well for him on Wednesday and there are many more caps to come."
Ireland will be looking to continue a good recent run of form when they face Chris Coleman's Dragons.
Giovanni Trapattoni's side have lost just once in 2013 - to World and European champions Spain - and face crunch World Cup qualifiers against Sweden and Austria next month.
The Italian has painful memories of Wales having seen his Italy side lose 2-1 at a sold-out Millennium Stadium during qualification for Euro 2004, and has warned his side the game will be a friendly in name only.
"This is no friendly," he said.
"I know this country. I was here many years ago with Italy, as was their scorer that night, (Craig) Bellamy.
"We won in Italy but we lost over here and we know about this team, I have seen so many games and I know the Welsh players, they have a good mentality and they are international players.
"After this game we can reflect, and we will know from our attitude and personality whether we are ready to play against Sweden."
Sunderland Premier League Fixtures
Saturday August 17
15:00 Premier League Sunderland v Fulham
Saturday August 24
15:00 Premier League Southampton v Sunderland
Saturday August 31
17:30 Premier League Crystal Palace v Sunderland
Saturday September 14
15:00 Premier League Sunderland v Arsenal
Saturday September 21
15:00 Premier League West Brom v Sunderland