The URC match takes place at MacHale Park
Connacht Rugby has confirmed the province's interprovincial derby against Munster in Castlebar in March is a sell-out.
Over 25,000 tickets have been sold for the URC match, which will take place at MacHale Park.
Connacht's previous attendance record is 9,120, set at a Champions Cup fixture in 2011.
The game, which takes place on March 29th, is eight days before Mayo play Sligo in the Connacht football championship at the same venue.

Arsenal March Into Champions League Final
Wednesday's Sports Update
Kildare U20 Football Team vs Louth
Phil Foden Agrees New Contract In Principle With Manchester City
Jerry Cahir To Join Connacht From Leinster This Summer
Hugo Keenan Commits Future To Leinster And IRFU For Another Two Seasons
Heimir Hallgrimsson Includes Seven New Faces To Upcoming Training Squad
Kfm Accounts Dept Vacancy