While the former Hurricanes and Toulon star, signed as short-term injury cover for Conor Murray, will be given until towards the end of the week to prove his fitness, Munster head coach Johann van Graan is preparing for the possibility that he will be without yet another quality number nine for the difficult Heineken Champions Cup pool trip to the English Premiership leaders.

“Hopefully, we'll know later today or tomorrow, but he is a concern, yes,” van Graan said this afternoon. “We'll give Alby as much time until we know more.”

The Munster boss confirmed that first-choice scrum-half Conor Murray and back-ups James Hart and Neil Cronin were unavailable for the Pool One opener at Sandy Park and that likely starter Duncan Williams, who replaced Mathewson in the 74th minute at the Aviva Stadium last Saturday, had also received a knock during his short time on the pitch in the 30-22 defeat.

“Duncan Williams also took a hit to the leg, but he should be fine. We've got (academy scrum-half) Jack Stafford who played pretty well for the A's (against Scarlets A last Friday), he should be the next guy in line.

“That's the beauty of the squad. The next guy is in and you've got to perform.”

The positive news for Munster, though, is the return to contact training of injured trio Marshall, Ryan and Bleyendaal.

Hooker Marshall suffered a calf injury in the win against Ospreys in Cork on September 14 following tighthead prop Ryan’s removal that evening with an ankle complaint.

Bleyendaal’s absence has been more significant, the Irish-qualified playmaker having been sidelined with a neck injury since February 23 and while his return to full team training marks a major step forward, there is still no definitive date for a return until he has emerged from taking contact to the satisfaction of Munster’s medical staff.