Wales flanker Ellis Jenkins' comeback from a serious knee injury has been delayed until around March 2020.
Jenkins suffered a knee problem in November 2018 against South Africa that has forced him to miss 2019, including the World Cup.
"He's going through his protocols," said Cardiff Blues head coach John Mulvihill.
"I don't want to put time frames on it but we're hoping to see him February or March, some time like that."
Jenkins, 26, had targeted a return for the 2019 Christmas derbies but Mulvihill insisted there should be no concern over his long-term future.
"He's doing well and from what I've seen he's strong and getting his fitness back," said Mulvihill.
"You don't want to rush these things, you want to get it right once."
There was more encouraging Blues back-row news with Josh Navidi set to return for the Boxing Day derby against Dragons.
Blues had hoped to have Wales flanker Navidi back for the first time this season in the 19-16 win against Ospreys.
Navidi had not fully recovered from the hamstring injury suffered in the World Cup quarter final win over France.
In Navidi and Jenkins' absence, Shane Lewis-Hughes has emerged - and the flanker has signed a new three-year deal with the Blues.
The 22-year-old was named in Wayne Pivac's first Wales' squad against the Barbarians in November and has continued this fine form with a man-of-the-match display against Ospreys.
Mulvihill believes Lewis-Hughes could feature in the 2020 Six Nations squad.
"He wouldn't let you down, that's for sure and if there's one or two injuries, he has a big chance of being involved in it [Six Nations]," said Mulvihill.
"I know Wayne was impressed with him. If it's not the Six Nations, I hope that he could be on a plane to New Zealand later in the year."