The picturesque setting of Monastery Field, the Clifden home of Connemara RFC, will be the venue for the opening game of the AIB Cup, which is in its fourth year.
There will be some added bite to the clash of Connemara and Barnhall as both sides are competing in Division Three of the AIB League this term.
Barnhall were relegated from Division Two last March, finishing bottom of the table, while Connemara won three of their last four games to finish in fifth place in Division Three.
Barnhall have been the busier of the two in the transfer market with Jamie Kavanagh (Portlaoise), William Reynolds (North Kildare) and South African Hendrik Crafford joining the club, along with three French players.
The County Kildare outfit have suffered three defeats in the pool stages of this season's Leinster Senior League Cup. Last Saturday at Parsonstown, they went down by 50-7 to Lansdowne and in previous weeks they were second best to both Greystones and UCD.
With Benjamin Bester from South Africa their only new recruit, Connemara have largely kept the squad from last season.
They have little form coming into Saturday's game with three straight defeats in the Connacht Senior League. They lost 29-11 at home to Buccaneers last weekend.
The Galway men lost 17-14 away to Wanderers in the first round of last season's AIB Cup. That same day Barnhall were beaten 20-13 by hosts Corinthians.
Neither side has ever reached the second round of the competition. The prize for Saturday's winners is a second round trip to either Nenagh Ormond or Lansdowne on November 1.
Trinity have the divisional edge on the visitors, as a Division Two side. They have also made a promising start to the new campaign. reaching the quarter-finals of the Leinster Senior League Cup thanks to two wins in three outings.
Tries from prop Tristan Goodbody and flanker and captain Shane Young helped them beat Navan 14-0 in their final pool game of the competition last week.
Division Three challengers Carlow opened their season with a 27-11 win over Skerries in the Leinster Senior League Cup. In recent weeks, there have been reversals to Wanderers and Terenure College. Last Saturday they lost 20-6 to Terenure at Oak Park.
Carlow were pipped 16-13 by Midleton in the first round of last season's AIB Cup. Twelve months ago, Trinity scored a notable 23-17 opening round success over Sunday's Well before falling to Clonakilty (19-3) in the second round.
Whoever wins at College Park on Saturday will face a trip to either Naas or Ballynahinch in the second round in November.
2008/09 AIB CUP - FIRST ROUND:
Saturday, September 20 -
Connemara v Barnhall, Monastery Field, kick-off 4pm
Dublin University v County Carlow, College Park, kick-off 5pm