Connacht centre Sammy Arnold is out of the game until April after undergoing surgery on a chest muscle injury, while Bundee Aki is set to train next week.
It's a blow for Arnold, who has gained a second wind since leaving Munster to ply his trade at the Sportsground. He was excellent in the win over Leinster in the Pro 14 over Christmas.
The better news from an Irish perspective is that Aki is set to become available for the Six Nations Championship.
The Ireland centre will miss Sunday's match with the Ospreys in Galway but is expected to be back on the paddock in a matter of days after recovering from a knee injury.
Paddy McAllister has a hand injury and will also be sidelined for the visit of the Ospreys.
Connacht are currently second in Conference B of the Pro 14, with five wins and four defeats from their opening nine matches.