Chris Farrell's rehabilitation from a knee injury is not going as quickly as hoped, according to Munster coach Johann van Graan.
The centre produced a man-of-the-match performance in February's Six Nations game with Wales but subsequently injured his knee in training and missed the rest of the season.
Munster now face into two interprovincial derbies and two European games without any sign of Farrell returning to boost Van Graan's midfield options.
"We won't see him before the Champions Cup starts but hopefully before Christmas," Van Graan, speaking at the launch of the Champions Cup season, told RTÉ Sport.
"I don't have the exact timings, those injuries [ACL] are difficult to judge.
"He won't be back anytime soon. He's mentally very well, he's working very hard off the field but in terms of returning to train with the team, he's still a long way off."
Asked if the 25-year-old, who has three Ireland caps, had sufferered a setback in his rehab, Van Graan responded: "I won't say setback, it's just slow.
"All the clever guys, medical guys that do these things, have got certain points of return and certain stages, certain players are better than others.
"You've got to slow down the rehab so he had a stage where he went really well and they have just had to slow down the rehab a bit.
"He's still within the time-frame of a standardised injury but we are just taking it day by day with him. It's such a big injury, you don't want to put him in there too early.
"You can't guarantee that it won't happen again but you certainly don't want to push such a big injury."
Keith Earls may return for Saturday's game against Ulster, but Van Graan could not elaborate on Conor Murray's injury.
The South African added that he expects to know more about the availability of Murray stand-in Alby Matthewson, who requires a work visa.
"I hope to have some clarity within the next 24 hours. It might be a chance that he will be in over the weekend," he said of the New Zealander, who has five All Blacks caps.
"He's been part of training, I think he is an experienced player and that's why we got him in.
"He's still in incredible physical nick, I think he brings a lot of calm.
"At the end of the day, it's a new player, he's got to prove his worth on the field, he's very excited to play once he gets that opportunity and hopefully, he will add to the team."
Meanwhile, Leinster coach Leo Cullen says that Sean O'Brien, who hasn't seen any action since a short run-out in April, is looking "pretty sharp" as he continues to recover from a shoulder injury.
"He's not a million miles away yet," said the Champions Cup-winning coach.
"He trained a good bit last week, stepped it up yesterday so we'll see if he came through from that so he's looking pretty sharp."
This Saturday sees Leinster travel to the Sportsground to face Connacht.
We need your consent to load this Facebook contentWe use Facebook to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences