The draw, made in the Dublin offices of tournament organisers ERC (European Rugby Cup) was overseen by Mark Egan, the IRB's Head of Rugby Services.
Michael Bradley's Connacht side, who bowed out of last season's Challenge Cup at the semi-final stage to eventual winners Sale, were a top seed in the draw, and therefore, were kept apart from fellow seeded teams: Agen (France), Gloucester (England), Viadana (Italy) and the Borders (Scotland).
Connacht have never played Worcester, who lost to Brive in 2004/05's round one, or Catania, 56-point aggregate losers to Sale in the first round last season, before, but easily accounted for Montpellier in last season's second round, thanks to a 56-3 first leg romp over the French side at the Sportsground.
The five pool winners and the best three runners-up will qualify through to the 2005/06 Cup quarter-finals.
The quarter-finals and semi-finals will be one-off matches played at home venues and the final at a neutral venue on the weekend of May 20/21, 2006.
The new pool format, which will provide each of the 20 participating clubs with a minimum of six games (three home and three away), will replace the previous season's knock-out structure and the European Shield tournament.
2005/06 European Challenge Cup Pools:
Pool 1: Viadana, Narbonne, Northampton Saints, Bristol
Pool 2: Agen, London Irish, Rugby Parma, Pau
Pool 3: Gloucester, Bayonne, Toulon, Bucuresti
Pool 4: The Borders, Brive, Newcastle Falcons, L'Aquila
Round One: October 21/22/23, 2005Round Two: October 28/29/30Round Three: December 9/10/11Round Four: December 16/17/18Round Five: January 13/14/15, 2006Round Six: January 20/21/22
Quarter-Finals: April 1/2Semi-Finals: April 22/23Final: May 20/21