He played only three games in the first half of the season but has since made 13 consecutive appearances on the right wing and Sunday's final will be his 29th NRL game in total. He has grown with each outing and in 10 of the last 13 he's run for more than 100m and scored five tries, including one in the 20-12 defeat of Melbourne last weekend.
He need look no further than the other side of the park for guidance and inspiration. His team-mates call him the Mini Beast, but at 9kg lighter and 6cm shorter, Tupou won't ever rival Vatuvei's vitals. He's trying to do it with the way he plays.
The pair regularly shoulder much of the burden to get their side out of their own territory early in the tackle count and Tupou has also shown an ability to jink his way out of trouble.
"He's been outstanding over the last few weeks,'' Vatuvei says. "He's done a lot. A few call him the Mini Beast. He's been real strong.
"Every run he's done, he's done well. We work off each other. Whenever he does a good run, I try one off the back of that and he does the same. We try to work together.''
Tupou has been with the Warriors since 2008 and enjoyed considerable success playing for the juniors in the Toyota Cup. But he missed out on playing in their grand final win last year because he had played too many NRL games.
He's not going to miss the Big One this weekend. He feels like an NRL player now - grand final week has that effect on people - and his attitude is good.
"You have to go hard in every game,'' Tupou says. "You have to train hard, do everything hard. Just show the coach you are willing to play for the team.
"I am going to cherish this whole week. Just enjoy it but when it's time to play, it's full-on from there. I just want to play my heart out and do whatever I can to help us win.''
If he can do that, a few might even bang the hoardings for Bill Tupou.