Conor Murray has suffered a 'low-grade' leg injury according to Munster but it is hoped he will return to action next week.
Lions boss Warren Gatland will be waiting anxiously over the next number of weeks as the club season ends and his picks for the South Africa tour negotiate important fixtures.
With scrum-half Murray set for a pivotal role for Gatland in South Africa, the news will be welcomed by the Lions management.
Murray will sit out Friday night's must-win Rainbow Cup clash with Cardiff Blues and Munster coach Graeme Rowntree said: "Yeah, hopefully he'll be all right for next week.
"He's certainly not in our plans this week, we'll see how he progresses."
Munster's hopes of progressing to the inaugural final of the tournament against South African opposition took a massive hit when they lost to Connacht last time out.
"It seems like a month ago now," sighed Rowntree.
"Yeah, disappointing but we move on and learn what we can from the game, manage our frustrations.
"I thought they played well. They stuck in the game right to the end, Connacht. But we've learned plenty from that game."
Asked if the Reds had figured out how their levels dropped after the opening victories over Leinster and Ulster, Rowntree replied: "Yeah, we figured it out thanks.
"We reviewed it and changed things accordingly, that's what you do, you move on quickly, take your learnings, take your medicine and move on, and we've done that."
What it means is that even if Munster win their final two games, their destiny will be decided elsewhere.
"It's irrelevant, any other results. It's about us, isn't it," said Rowntree.
"It's about us getting things right after that game, there's disappointment but as I said, they played well, they stuck in right until the end there, Connacht.
"But it's irrelevant, the results, it's getting our game plan and our process right, that's all we can do."
