Nathan Cleary has hailed Bevan French a "freak" after watching his fellow Australian wizard produce the moment of magic that delivered another Super League triumph to world champions Wigan.

From one grand final winner to another, it was the ultimate compliment.

A week and 17,000km distant from his own masterful performance in Penrith's NRL triumph, Cleary was in the Old Trafford stands on Saturday awed by how French, who'd shone in Wigan's World Club Challenge win over his Panthers, had dazzled once more.

With the only try of a bruising, absorbing contest, French's solo brilliance, as he skinned three defenders to break the scoreless deadlock in the 23rd minute, ensured Wigan downed Willie Peters' gallant Hull KR side 9-2 in the British game's showpiece in front of 68,173 fans.

In the process, the 28-year-old one-time Parramatta flyer became the first man to win player of the match awards in the World Club Challenge, Challenge Cup and Super League finals in the same year.

It left French on the verge of tears after he'd produced his tour de force in front of some of his family, who had been specially flown in to Manchester by the club to see him inspire Wigan to become the first team to win all four big trophies in the same British rugby league season.

And Cleary, who was in town for a bit of a holiday with soccer star girlfriend Mary Fowler, loved what he saw from another superlative halfback.

"I thought Hull were starting to win the field position, but then, ah, Bevan French, he's a freak...," Cleary enthused on Sky Sports.

"He broke the game open, and every time he touched the ball, he looked pretty dangerous."

French's try, aided by two successful kicks from fellow Aussie, former Sydney Roosters player Adam Keighran, and a Harry Smith drop-goal nudged coach Matt Peet's history makers to the seven-point win.

Rovers, coached by another Australian Peters, had been after their first domestic title in four decades, but couldn't take their chances to crack the mighty Wigan defence and had only a penalty from Mikey Lewis to show for their efforts.

Yet it was French who lit up the match in the moment he produced a little feint as if to pass, only then to dart between two markers including Lewis - who had succeeded him earlier in the week as the British game's 'Man of Steel' as player of the year - and slalom his way past one more flailing defender en route to the line.

"It's been an emotional week. We knew history was on the line, being the first to go all four (Super League, League Leaders' Shield, Challenge Cup and World Club Challenge) in the calendar year," French told Sky TV, close to tears.

"This one just meant more. The club went above and beyond to surprise me by flying my brother and uncle over. It's special, I'll never get to feel like this again.

"It's a pleasure to be a part of this club, not only for now but throughout this year, the past four years and for the next four years."

That sounded like a message to the NRL clubs who have been keen to woo back the Indigenous star who had entertained British reporters in the week with tales of how he had learned his bag of tricks on the bone-hard pitches around his Tingha, NSW, home.

But French reckoned it was good old-fashioned defensive grit, not his champagne moment, that won the day.

"This is the second grand final in a row where we haven't conceded a try. It's great to achieve this, but collectively it's the defence that has definitely won it for us."