The second row is suffering from 'a little hip problem' according the Munster coach Declan Kidney.
Speaking after his side's 9-8 victory over the Ospreys, Kidney explained: "After the Captain's Run session on Friday, Paul went home and felt sore. He has a little hip problem and wasn't good to go. We'll have to see how he pulls up over the next 48 hours."
Flanker Niall Ronan was also a late cry-off for the Ospreys game, with John O'Sullivan stepping in to don the number 7 jersey.
"Niall woke up with a back spasm on Wednesday morning, trained Friday but said he could only run at 90%. That was an honesty call from him," Kidney said.
"Hopefully both Paul and Niall will present themselves up for selection next week."
Out-half Ronan O'Gara, the Heineken Cup's record points scorer, is on course to start the clash with Saracens as he is making a swift recovery from the knee injury he picked up against Leinster two weekends ago.
Kidney described Saturday's result as a 'huge win' and had praise for O'Gara's two deputies, Paul Warwick, who kicked all of Munster's points, and his replacement Jeremy Manning.
"It was a huge win because what we want to try and do is show a level of consistency. We'd lost two home Magners League games and they're going to be very costly to us by the end of the season," the Corkman added.
"We want to put on a good show all the time, especially at home because the support (tonight) was brilliant especially in the first half. It would have given any team a lift.
"And again in the second half. Even though it rained, nobody was leaving early. That type of support deserves our best efforts and it gives everyone in the dressing room a lift."
Asked about his out-halves on show, he said: "Paul did very well, but a guy who is doing very well in the background too is Jeremy Manning. They've been pushing one another along. There is that competition for places.
"We're trying to make it a squad whereby we don't become a one or two-man team. All those players coming through are vital for the good of the team. I also like to think they help one another to become better players."
Meanwhile, the remaining tickets of Munster's allocation for the Saracens v Munster Heineken Cup semi-final (Ricoh Arena, Sunday, April 27) will go on sale on Monday morning in Cork and Limerick.
The tickets, priced at 27 euro, will go on sale at just one outlet in each city - in Cork at the Munster Rugby Store on Maylor Street and in Limerick's Munster Rugby Store on O'Connell Street. Both stores open at 9.30am.
(Payment terms - Cash only accepted. No credit cards accepted).