Youngster David McSharry hangs onto his place in the squad after an impressive performance in his first start for Connacht.
While this is Connacht's first match in the competition, the squad still boasts considerable Heineken Cup experience.
Captain Gavin Duffy is one of five players who have played in the Heineken Cup previously. The full-back spent three seasons at Harlequins including the 2004/05 Heineken Cup campaign where he scored a try against Castres Olympique in the pool stages.
Scrum halves Frank Murphy and Paul O'Donohoe have played for Leicester Tigers and Leinster respectively, while Thomas Anderson and Niall O'Connor have both previously lined out for Ulster in the Heineken Cup.
While the rest of the squad may not have Heineken Cup experience, there are six players included with over 100 caps for the province. Heading that particular list is lock Michael Swift who has 204 caps to date.
CONNACHT Squad (v Harlequins) - Backs (12): Frank Murphy, Paul O'Donohoe, Niall O'Connor, Miah Nikora, Henry Fa'afili, Eoin Griffin, David McSharry, Tiernan O'Halloran, Fetu'u Vainikolo. Brian Tuohy, Matthew Jarvis, Gavin Duffy.
Forwards (14): Brett Wilkinson, Ronan Loughney, Rodney Ah You, Dylan Rogers, Adrian Flavin, Ethienne Reynecke, David Gannon, Michael Swift, Mike McCarthy, Thomas Anderson, Eoghan Grace, John Muldoon, Ray Ofisa, George Naoupu.