Scarlets hooker Ken Owens hailed the return from cancer by former team-mate and Cardiff Blues captain Matthew Rees ahead of their Pro12 derby match.
Owens could face Rees when the Cardiff Blues host the Scarlets at the Millennium Stadium on Sunday.
"The work he's put in in the last six months and the dedication to want to get back is phenomenal," said Owens.
"He's had his goals that have pulled him through and it's great to see him back and fighting fit."
The Blues face the Scarlets in the first game of the all-Welsh double-header billed as 'Judgement Day', which is followed by the Newport Gwent Dragons' clash with the Ospreys.
Owens, who was won 24 Wales caps, was Rees' understudy for seven years at the Scarlets until the former Wales captain signed for the Blues in 2013.
"It'll be great to see Matthew back on the pitch - he's a great player," said Owens. "It'll be interesting. I haven't played against him before.
"I have nothing but admiration for him as a player - not only in what he's gone through and overcome in the last six months but throughout his career. I've learned so much off him over the years."
Owens admits that Rees, who has won 57 Wales caps and was a Lions Test starter in 2009 in South Africa, had a huge influence on his early career and development at the Scarlets.
"Matthew taught me some lessons whilst scrummaging against him during training, I learned from that," said Owens.
"He was massive in my development. He went on a Lions tour which ultimately gave me an opportunity. You learn from the best. I would like to think that it helped him to have me nipping at his heels, too."