There are, of course, more obvious candidates; few would be surprised if Gareth Ellis, the inspirational captain, gave a typically influential display to aid the East Yorkshire club to a first Wembley win in their 151-year history.
Similarly, if Warrington Wolves were to prosper, and continue their own treble aspirations at the expense of Hull, either of their pivotal Australian half-backs –Kurt Gidley and Chris Sandow – would be an obvious pick.
However, given the recent form of explosive 11-try centre Fonua, he is undoubtedly a fine outside bet.
Someone who knows the hulking three-quarter well is Hull colleague Sika Manu who, like his fellow Tongan international, made the move to Super League from the NRL ahead of this season.
Second-row Manu, one of this competition’s finest acquisitions, joined from Penrith Panthers, but had previously played alongside Fonua for Melbourne Storm.
While Manu was rested for last Thursday’s 44-0 win versus Catalans Dragons, which confirmed the leaders a top-four finish, his team-mate was causing carnage once more, just like he has done for most of this campaign.
“Mahe was outstanding again against Catalans and he has been for the last few weeks,” said Manu, who has forged arguably the most dynamic right-edge in the competition with the hard-hitting 23-year-old.
“He’s an awesome player to play alongside. I was lucky enough to play with him on his debut in the NRL and we’ve had a connection for a long time.
“I watched him come through the ranks at Melbourne and he has always been a talent, but this year he’s just really matured and bloomed really well.
“Mahe’s killing it for us. He’s been awesome and every time he touches the ball he does something positive so, hopefully, he can carry that on. If we can get him some ball I think he’ll do some damage to Warrington.”
Manu was in the same side as 19-year-old Fonua, who made that NRL bow in 2012 during a 24-16 win over Gold Coast Titans, becoming Storm’s first Victorian born-and-bred debutant with current Hull team-mate Steve Michaels, ironically, scoring for the opponents.
“Sometimes I forget how young Mahe still is,” added Manu, who left for a three-year stint with Penrith soon after. “I got to play with him and to now see him grow over this time, it is a huge rap to him.
“To be doing it on the big stage together this week, I am really looking forward to it.”
Manu, who won the 2012 NRL Grand Final with Storm, will look to bring all his experience to bear this weekend.
“I’ve had a few finals and it’s good to have a few leading into a big game like this,” admitted the 29-year-old, who was also a beaten NRL finalist against Manly Sea Eagles in 2008.
“Hopefully I can pass on a bit of experience to the younger boys. Personally, I’ve just been happy to come to a really good club in my first year over here, a bunch of really great blokes and awesome players.”
He was afforded a rest during that Catalans win, only the second game he has missed in the last 15 since sitting out the Challenge Cup sixth-round victory at St Helens in May to head back to Sydney and captain Tonga against a Samoa side led by Hull back-row colleague Frank Pritchard.
“I’m just resting a few little injuries that I’ve been playing with for a couple of months now so it was just a good chance to get the week off and get ready for Wembley,” he explained, having scored three tries in his 24 appearances.
“When I first came over I didn’t realise how massive this competition was but I know a lot about it now. The more time I spend here the more I get to know and learn about it.
“Now I know it’s a massive thing for everyone in Super League and, hopefully, we’ll get the job done on Saturday.
“I also know Hull have never won at Wembley; it would be good to put our names in the history books and, if all goes well, that will happen this week.”
Manu, who played for New Zealand in 14 Tests before deciding to represent his Tongan heritage, knows, though, there are few weak links in a Warrington side who are challenging them for the Cup, League Leaders’ Shield and Grand Final.
“They’re a really tough team all over the field,” said the player who has, along with Hull’s fellow 2016 NRL recruits Fonua, Pritchard and Carlos Tuimavave, had an instant impact for Lee Radford’s side. “The two times we’ve played them they’ve been really close games (that Hull have won narrowly). It’s never easy against them but, hopefully, we’ll do the same on Saturday and get that win. It’s an exciting prospect.”