Popoali'i lit up the tournament last year and was subsequently picked for the national side. He was then picked as a wider training squad member for the Highlanders and has spent the past few weeks training full time with the Super 15 franchise.
But he has been given permission to play sevens by Highlanders coach Jamie Joseph and will be a real asset to the Otago team this weekend.
The Otago side also welcomes back Paul Grant this season, who did not play the abbreviated form of the game last year.
Brad Cameron also turns out for the side this year.
Otago coach Roy Hawker said players had put their hands up wanting to play and having the likes of Grant and Popoali'i in the side was a boost.
Southern midfield back Luke Herden had trained well with the team and would be playing in the forwards.
Taieri midfielder Kieran Moffat would also play in the forwards.
The side had trained for the past eight weeks but had a spell over the Christmas period for players to spend time with family.
It had its first training run back together on Monday night.
Hawker said defence was obviously important in the game and his team needed to have a belief it could match the aggressive North Island sides.
Hawker said the game was about accuracy and taking all the chances which came along.
Popoali'i, Joe Hill and Brad Weber would act as playmakers with Tony Ensor, Marshall Suckling and Matt Faddes to provide speed on the outsides.
Otago won the South Island tournament in November but has played no tournaments since while North Island sides have had competitions in which to play.
Otago has Taranaki, Horowhenua-Kapiti and Southland in its pool, with the top two teams qualifying for the top section on the second day.
Otago first plays Horowhenua-Kapiti at 1.10pm on Saturday and then takes on Taranaki at 4.10pm before facing up to Southland in the final game of the day on Saturday, at 6.50pm.
Taranaki was last year's beaten finalist and won the North Island tournament in Mt Maunganui last weekend.
Auckland won the tournament last year and is expected to do well again.
Otago squad
For nationals
Otago: Paul Grant (captain), Josh Clark, Brad Cameron, Kieran Moffat, Luke Herden, Tumua Ioane, Brad Weber, Joe Hill, Buxton Popoali'i, Marshall Suckling, Tony Ensor, Matt Faddes.
