A week ago, Mate Ma'a Tonga were $81 outsiders to win the tournament, although most thought they would put on a decent show, especially in their typically fierce clash with island rivals Samoa.

Now they are a $31 hope thanks to the recruitment of Jason Taumalolo, the best forward in rugby league, and Andrew Fifita, the Sharks, Blues and former Kangaroo player who decided to make a late switch of allegiances, a move that came with the blessing of Australian coach Mal Meninga.

Will Hopoate, Fifita's new teammate, believes both are doing it for the most genuine of reasons. One has deserted the tournament favourites, the other the second elect. Both will forgo decent sums of money in the process, with Fifita missing out on $50,000 should the Kangaroos salute.

Whatever the reason, the result will be a Tongan forward pack that should not only rattle a few cages but potentially the ground under their boots. While their key playmaking roles remain a concern, Tonga should be able to match it with the best in the tournament when it comes to size, explosiveness and power.

"They're definitely a great team," Australian backrower Wade Graham said, while Kiwi coach David Kidwell declared them genuine contenders. "[Taumalolo and Fifita] certainly add to any team they play in. Obviously a lot's happened today. It's all hard to digest right now."

Taumalolo needs little introduction. He's become so good that any team he plays in suddenly becomes a chance of winning. Despite having an indifferent grand final, he was the standout big man of the game in 2017, becoming the first forward in NRL to crack 5000 running metres.

Joining him is Fifita, who may have made a smart move not only in terms of his cultural ties but his time on the field. Given the ups and downs of his season he may not have found himself in Meninga's best 17, so from a football sense it looks the right play.

His 2017 highlight was without doubt his game one effort in Origin, a match he may not rival in his entire career. Everything went right on that occasion and it showed how dominant he can be when he's fit, firing and ready to play.

His form was mixed from that point and into the finals. But he remains a quality player, with plenty of big-game experience which can help lead the way for a Tongan pack that should have rivals firmly on notice.

The support cast is impressive. Manu Ma'u is another who has turned his back on New Zealand to link with Tonga. The Eels backrower was in damaging form for much of the year, becoming an 80-minute player for Brad Arthur.

Former Roosters prop Sam Moa, now with Catalans, adds further bulk and will smash into the defensive line at pace. Broncos forwards Joe Ofahengaue and Tevita Pangai jnr bring some youth, and now have finals experience.

Rounding it out will be Roosters backrower Sio Siua Taukeiaho???, who was a wrecking ball at times for the tricolours in 2017 and will be hard to handle in any of their pool games against Scotland, Samoa and New Zealand.

They will rely on Wests Tigers playmaker Tuimoala Lolohea and Warriors half Ata Hingano to lead them around the park.

Tonga's big guns

Jason Taumalolo

191cm, 113kg???

5350 run metres, four tries.

The standout forward in rugby league. Brings Tonga instant respect, no matter the opponent.

Andrew Fifita

194cm, 120kg

3350 run metres, 53 offloads.

Took on the might of the Maroons in game one and prevailed. Mixed form late in the season, but a huge addition in every sense of the word.

Manu Ma'u

184cm, 103kg

2883 run metres, 29 offloads

Rising Eels backrower with a big motor who can set up a try from his strong runs on the edges. On the up.

Joe Ofahengaue

190cm, 112kg

1606 run metres, 339 tackles

Strong interchange campaigner for the Broncos who rose in stature in the finals.

Tevita Pangai jnr

190cm, 188kg

1519 run metres, 33 offloads

Injury interrupted his season, but Wayne Bennett has enormous hopes for this young bull of a forward. Has the size and the skill to become something special.

Sio Siua Taukeiaho???

184cm, 101kg

2105 run metres, 379 tackles

Only played 17 games in 2017, but ran for 100 metres-plus in the past five games, two of which were finals. Plays his football hard and fast. Should be a perfect fit for the Tongans.

Full Tonga squad

Andrew Fifita, Mahe Fonua, David Fusitu'a, Siliva Havilli, Ata Hingano, Will Hopoate, Konrad Hurrell, Michael Jennings, Solomone Kata, Sione Katoa, Samisoni Langi, Tuimoala Lolohea, Sika Manu, Manu Ma'u, Sam Moa, Ben Murdoch Masila, Joe Ofahengaue, Tevita Pangai jnr, Ukuma Ta'ai, Sio Siua Taukieaho, Jason Taumalolo, Peni Terepo, Daniel Tupou, Manu Vatuvei.