Sean McMahon: Rennie instrumental in my Wallaby return

For four years Sean McMahon has been watching Australian rugby from afar, but the mercurial back-rower says he hasn't lost a step.

Three years in Japan's top flight with Suntory Sungoliath has brought a new level of discipline to his game and the 27-year-old has been rewarded with a Wallabies recall for Saturday's Rugby Championship clash with Argentina.

High-intensity workouts within hotel quarantine has peppered McMahon to be "the fittest in this team" as described by coach Dave Rennie last week, with the rampaging back-rower highly excited to get amongst international Test rugby again.

"Japan has done wonders for me (and) for my body," he told reporters on Monday.

"I'm feeling fresh and it's been good for me up in Japan, do a lot of running over there, it's very fast game and I am looking forward to the contact side of things back at international level to see if I'm still capable of standing up with the big dogs."

McMahon last donned the gold jersey in November 2017 against Scotland with a different and older crop of players around him.

He says learning names, faces and competing for spots with the new wave of Wallabies talent is an exciting prospect two years out from the World Cup.

"Nearly classify myself as an old bull now that there's so many young faces around," he joked.

"There's plenty of competition especially in this environment at the moment, a lot of youth and then you've got the experience of Hoops (Michael Hooper).

"It pushes you to want to learn quickly and get your head around everything. Those boys have been more than willing to help me out and try to get my knowledge up to speed as quickly as possible."

With the relaxation of the Giteau Law, which stopped players under 60 Test caps and seven years service from being picked while playing overseas, McMahon said it was his new coach that brought him back into the fold.

"Everyone misses throwing on the gold jersey when they don't have the chance to put it on anymore," he said.

"Dave and me were talking on and off about trying to get me back and things just kept falling out of place with things in Japan, Australia, stuff like that ... COVID didn't help, that's for sure.

"It's always nice to know that there are people and coaches around that still want you to be back and ... have a crack.

"It just gives you more motivation when you're overseas. For me, to train and make sure that I was up to scratch if there was ever an opportunity for me to come back."