Sam Warburton remains on course in his recovery from injury but has not been given a comeback date.
The British & Irish Lions captain tore his hamstring in the second Test against Australia in June.
Warburton was given a rehabilitation period of up to 16 weeks from the time of the injury in Melbourne.
That would see the fearsome flanker potentially available for the Blues' Heineken Cup round two clash against Toulon - three week's ahead of Wales' opening autumn international with South Africa.
The 24-year-old is progressing well but remains in the dark over a specific comeback date.
"I'm on schedule. I started jogging last week - just some light stuff to try to load the hamstring and no reaction to that so far," said Warburton.
"They said 16 weeks to star, but the physio has said that until we tick certain boxes he can't give me a return date yet.
"It is 50% jogging at the moment and then I will up it to 60%, 70% and more. Then you have to put in some contact.
"There are a lot of things I have to do, and a lot of boxes to tick, before I get back. I've asked for a return date, but they've told me there is a lot that could happen in the next six weeks or so as I progress in my rehab and get more aggressive with it.
"What's difficult for me is that I haven't been given a target fixture for a comeback. It means I will just have to see how the re-hab goes, which is pretty boring.
"Some players have a bit more difficulty getting back to top speed when they come back from hamstring injuries, while others shave a few weeks off their recovery time.
"The honest answer is 'I don't know when I'll be back'."
And Warburton is well aware that a swift return is imperative with both the Blues and Wales boasting a wealth of talent in the back-row.
At the Arms Park new Wales caps Josh Navidi and Andries Pretorius will be aiming to build on impressive seasons alongside Robin Copeland.
While Wales boast another four Lions back-row forwards in Toby Faletau, Dan Lydiate, Justin Tipuric and Ryan Jones.
"We have got the strongest back row selection in the northern hemisphere," added Warburton.
"It is a nice situation for the coaches to be in, but it makes it harder for me. I just need to get back playing for the Blues as quickly as possible."
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