Ireland trailed 21-3 at one stage before mounting a valiant comeback but it wasn't enough to deny the BaBaas a deserved victory.
Declan Kidney gave senior debuts to Ulster trio Chris Henry, Dan Tuohy and Ed O'Donoghue and Leinster centre Fergus McFadden in a side led by triple Lions tourist Ronan O'Gara.
But while O'Gara was one of the big-names in action on his home ground, Ireland were without a whole host of fellow Lions.
Tour skipper Paul O'Connell, Stephen Ferris, Keith Earls and Luke Fitzgerald are all out injured, while Shane Horgan and David Wallace were both late withdrawals.
Ireland captain and three-times Lions tourist Brian O'Driscoll was one of the high-profile Lions rested ahead of Ireland's southern hemisphere tour, as were Gordon D'Arcy, John Hayes, Donncha O'Callaghan and Jamie Heaslip.
Wales featured the majority of their Lions in their clash with South Africa but they weren't quite able to gain revenge for last summer's series defeat with Britain and Ireland's elite.
It looked as if Wales might emulate the Lions' third-Test win in Johannesburg as they led 16-3 with a quarter of the match played at the Millennium Stadium but a much-changed Springbok side showed the character associated with world champions to claim a thrilling 34-31 win.
Lions tourist James Hook was the afternoon's first try scorer and Alun Wyn Jones grabbed Wales' third, while fellow Lion Stephen Jones contributed 13 points with the boot as Wales came agonizingly close to securing just their second-ever win over South Africa.
A total of 10 Lions played their part for Wales with the aforementioned trio being joined by Lee Byrne, Leigh Halfpenny, Jamie Roberts, Mike Phillips, Matthew Rees, Adam Jones and Ryan Jones but Lions forwards coach Warren Gatland was ultimately left to rue a missed opportunity in Cardiff.
Wales at least had something to cheer about at the weekend thanks to the possible Lions stars of the future as their U-20 side opened their IRB Junior World Cup campaign with a 22-13 win over Samoa in Argentina.
England followed suit with a comfortable 48-22 win over the host nation in Rosario but Ireland were beaten 25-22 by France in heartbreaking circumstances as they conceded a late, late penalty after their own converted try had seemed to have snatched a draw.
Scotland were the second Home Nation to begin their campaign with a defeat as they were hammered 58-13 by an impressive-looking Australian outfit.