A statement released by Ulster Rugby on Tuesday indicated that the loose-head would see a surgeon later this week for further opinion.

Michael Lowry sustained a concussion in the match at the RDS and will follow the return to play protocols.

Angus Kernohan is set to be out until mid-February with a hamstring strain.

McCall has endured a frustrating time with injuries in recent years, including a serious hamstring problem picked up against Clermont Auvergne in December 2016.

The 27-year-old had just battled his way back from a pre-season elbow injury to make his first start in almost a year at the weekend but his return lasted only 48 minutes before he was carried from the field.

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Academy player Eric O'Sullivan is set to reclaim the number one shirt for Saturday's key Champions Cup game against Racing 92 at Kingspan Stadium.

The Dublin native impressed in the European double-header with the Scarlets in December and had appeared in every game for the Irish province this campaign before Saturday's trip to Leinster.

The 23-year-old had not made a professional appearance prior to this season.

Ulster are set to welcome back all of their frontline players for the crunch Pool Four encounter, with the exception of forward Iain Henderson who is likely to be out of action until early March.

Included among the returning Ireland internationals will be Jacob Stockdale, who is the only player to have scored a try in every round of the tournament so far.

Ulster wing Robert Baloucoune has been registered with European Professional Club Rugby as an additional player following the departure of Australian Henry Speight.

Racing were convincing 32-point winners over Ulster when they met in October.

Dan McFarland's men will conclude their Champions Cup series with an away trip to Leicester Tigers on 19 January as they bid to reach the quarter-finals of the competition for the first time since 2014.