Anthony Foley's side will need home and away wins over Stade Francais and a victory over Treviso if they're to make the quarter finals.
That follows yesterday evening's 17-6 defeat away to Leicester.
Things are far rosier for Ulster who are second in Pool 1 with a game in hand after a superb 25-23 win away to Toulouse.
Connacht remain top of Challenge Cup pool 1 despite suffering their first defeat of the campaign.
Pat Lam's injury-ravaged side went down 29-5 away to Newcastle.
