Penrith backrower Liam Martin won't admit it to his face but he knows halfback Nathan Cleary is as tough as they come.
The Panthers' captain defying a shoulder injury to lead his club to successive NRL grand finals is no surprise to Martin.
Cleary injured his shoulder in NSW's State of Origin II triumph in Brisbane earlier this year.
Penrith's medical staff opted for rehabilitation and ongoing management over season-ending surgery, although Cleary is almost certain to go under the knife after Sunday's grand final against South Sydney.
Cleary's form has hardly missed a beat despite his ailment, with the qualifying-final loss to the Rabbitohs in Townsville last month the only fixture the 23-year-old has tasted defeat in all year.
"He's joked with me that he reckons he's tougher than me, and as a halfback he's protecting the back-rower," Martin told AAP.
"His toughness probably doesn't get highlighted enough.
"One of his best qualities is just how resilient he is.
"He hasn't even let on whether his shoulder's bothering him. Doesn't mention it at all to the boys.
"He's just one tough bugger."
Tough enough to endure a no-holds barred training session to test out the shoulder.
"There was a day there where Viliame Kikau kind of ran into him and he dusted himself off and everyone held their breath, but once he got up and laughed after that we all felt a little bit better," said coach Ivan Cleary on Saturday.
The coach lauded his son's ability to not only hide the injury during Origin II, but play on and find a way to finish the season.
"The fact that he hid that injury throughout the game showed the mentality of what was to come.
"We had a few opinions given to him afterwards that weren't necessarily all positive, so that was a challenging thing to get around but in the end our medical staff here, led by Pete Green, have done an incredible job.
"To Nat's credit he's been 100 per cent committed and constantly doing what he can to get himself into a position to play for his team."
Cleary's return in mid-August has also helped halves partner Jarome Luai, who battled with the burden of leading Penrith's attack in the halfback's absence.
The pair have won 55 of 58 games partnered together since the start of under-20s across all competitions, including State of Origin and NRL.
With his partner-in-crime back alongside him, Luai is himself finding his best form as the Panthers aim to erase the pain of last year's grand-final defeat to Melbourne and secure the club's third premiership success.
Luai says Cleary opting to play on with a sore shoulder is a reflection of the wider values throughout the team.
"It's all about heart and we've got plenty of that in this team," Luai told AAP.
"Nathan's the leader of our group and we've got his back."
