Meet Steve Mafi: The Tigers’ Tongan hitman

How's this for an accolade? "He was arguably the best No 8 in the world. The Welsh No 8 Mervyn Davies was of course much better known, and when Ireland's Ken Goodall sadly went to rugby league, Davies earned his top ranking among the major countries. But as Mafi showed in Britain, he was good enough to jump anywhere in the line-out... and he was quick enough to hold off the fastest of the Welsh backs in a 30-yard sprint. He was strong enough to scrummage well as a lock and he was a devastating tackler. He was almost a one-man team, and although that inevitably placed unfair pressures upon him, he was good enough to withstand them."

Who said that? The great coach Carwyn James – Saint Carwyn of Stradey, the One True King of Welsh sport – in a book written with the acerbic but hugely knowledgeable writer John Reason in 1979. Of whom did he say it? Sione Mafi, the captain of Tonga and the architect of a victory over the Wallabies in Brisbane six years previously that had sent rugby's tectonic plates smashing into each other. When you consider that, apart from Merv the Swerve, such blinding luminaries as Andy Ripley, Morne du Plessis and Jean-Pierre Bastiat were playing international rugby with the same number on their backs at around the same time, Mafi must have been one hell of a piece of work.

Funnily enough, the outstanding England prop Dan Cole used some of the same language – not the "best in the world" stuff, but the skill-set terminology – to describe Mafi's grandson Steve, who has made such an impact on Leicester's fortunes over the last nine months.

"Steve has the full range of gifts," Cole remarked this week after the first of his team's preparatory sessions ahead of today's Premiership final with Harlequins at Twickenham. "He can run, he can jump, he can tackle like a ton of bricks, he's good in the tight phases, he can multi-task. When he came to us last season – we had injuries in the second row and he was signed to see us through a difficult patch – he appeared for training wearing three rugby shirts. It was pissing down with rain, the water was running off his backside and I thought to myself: 'I feel sorry for you, my boy.' He didn't complain but, as we soon came to realise, he wasn't one to say much whatever the weather. And while he may have looked uncomfortable, he was pretty bloody effective once we started running around."

If truth be told, Mafi does not exactly talk the hind legs off a donkey now – so many Tongan players prefer to keep their thoughts to themselves – but if the 22-year-old, Sydney-born forward continues to progress at a rate that would spook Leicester themselves were it not so beneficial to them, he will soon find the balance of his rugby life tipping away from the private and towards the public.

"My grandfather passed away last year," he said. "I was born in Fairfield, one of Sydney's south-western suburbs, and he lived up in Brisbane – a coincidence, I guess, given what had happened there in '73. There's some footage of that match on the web and I've watched it a few times. Some of the tackling that day was as hard as it is now. It's a Tongan thing, I suppose, although I've only ever been to the islands twice: the first time when I was a little kid, the second time when I was in the national team and we got together ahead of the Pacific Nations Cup.

"My family come from Hihifo Kolovai and my father played his rugby there. He was the one who coached me in rugby, who gave up his time to help me make my way in the game. He'd work with me before a match and work with me after a match. He watches me even now, whenever there's footage available back home. If I do something wrong, I cop it on the phone pretty quick."

Mafi – 6ft 7in and well over 17st – might easily have been a Wallaby. He played age-group rugby for Australia up to and including under-20 level: such were his talents, he frequently operated both as a forward and a back in the same match, moving up front for scrums and line-outs before dropping back into midfield, where his pace and handling skill could be best utilised. But after spells of top-grade club rugby with Parramatta and West Harbour, plans to move into Super Rugby with the New South Wales Waratahs failed to bear fruit.

"I didn't know quite what to do," he recalled. "I'd enjoyed playing for Parramatta – it was good fun playing against someone you thought you recognised and then realised was a big-name Wallaby – but there were financial difficulties there and it looked as though the club might fold. I had an offer to play some league rugby in Italy, and then the Leicester thing came up. I didn't know anything about European rugby, so I asked my mates what I should do. They told me Leicester were one of the best teams around so I decided to give it a go."

By that time, he had pledged himself to Tonga and broken into the Test side, playing against Samoa, Fiji and Japan in 2010. "We lost all three, but only by a total of a few points," he said. "I hoped a taste of rugby in England would help me make the squad for the 2011 World Cup." He hoped in vain: in one of the more mysterious selection decisions of the age, he was overlooked for the big tournament in New Zealand. "I didn't hear a word from the coaches," he said. "It was my agent who told me I hadn't made it. 'Prepare yourself to go back to Leicester,' he said, so I did. I was upset at the time, but I knew I'd be playing some good rugby at Welford Road."

Good quickly turned into brilliant. Stripped of their World Cup personnel and further undermined by injury, the Midlanders barely won a game in the first two months of the season, but Mafi and his fellow southern hemisphere import, the Australian flanker Julian Salvi, slowly found ways of restoring the team to full competitiveness.

"There were moments early on when we would all be looking at each other with a 'what's going on here?' expression on our faces, but once we decided that it would be beneath us to use the absence of the World Cup boys as an excuse, we began to turn things round. There was never any loss of faith. You don't lose faith at this club.

"We've had our bad moments this season: conceding 40 points to Ulster in the Heineken Cup wasn't great, but that's what you get if you go half-arsed to a place like Belfast. Yet the stuff we've produced recently has been pretty special and anyway, this is always an awesome place to play. The rugby up here is more forward-oriented than it is in Australia, but that doesn't make it any less exciting when the ground is full of people roaring you on. So many people come out of this club as legends. I want to be one of them."

Having missed out on last year's global gathering in All Black country – how he would have loved to have been involved in his country's opening match with New Zealand in Auckland, home to a substantial population of Tongans – he is now back in favour at international level. "I'm in the squad for this summer's Pacific Nations tournament in Japan and I'd love to play," he said. If he does not, he will not be the only one left wondering what the hell and why. The entire Premiership community will demand an explanation.

One last question, then: does he expect a tier-one Test nation to pay a visit to the land of his ancestors any time soon? (The Scots are playing in Fiji and Samoa next month, but not in Tonga). "I can't say," he replied. "Tongan sport struggles for money and if there's no money to be made from travelling there, the big teams tend not to go. But when we bring all our best players together we can be competitive. We showed that in the 2007 World Cup and again last year. And the Tongan people live off their rugby. It's what we're known for, isn't it? I can't think of anything else."

The union game runs in the blood down there in the South Seas. Especially in the Mafi blood. If Sione was the greatest expression of Tongan rugby, his grandson is following in the family tradition.