Popoali'i played the final quarter of last week's game against Hawkes Bay at the back and will don the No15 jersey from the start in tonight's match against Tasman.
Popoali'i started there when he came into first-class rugby in 2008 but has become more of a winger in recent times.
''To be honest, I'd like to play first five. But that is never going to happen. I'm better off out on the wing or fullback. These days, they are pretty similar positions,'' he said.
''I would like to think I'm improving. I'm trying to tick all the boxes and do the right things. For me, not being the biggest guy, a lot of the focus this year has been on defence.
''Some of the wingers you face now are really big guys. I just have to chop them down and then get straight back up.''
Popoali'i has had a disrupted season so far.
Playing for the Highlanders, he was knocked out against the Blues, then was off the field for more than a month with a torn ligament in his foot.
''Andrew Hore and all his sprigs stood on me. It was in the game against the Reds and I kept on playing. Then in that game against the Blues I got knocked out. I was fine afterwards but my foot was playing up.''
He eventually got back on the park for the Highlanders - he has signed for the franchise again next year - but picked up a hamstring strain against Bay of Plenty in the first ITM Cup game of the season.
That caused him to miss the historic Ranfurly Shield challenge against Waikato.
''I just watched it at home. I knew the boys had it in them to beat them [Waikato]. It was great when we had it for those nine days but just a real shame we lost it.''
Popoali'i said the side was over the disappointment of losing the shield, and although the bodies took a while to recover, he was aiming for a big game against Tasman tonight.
The 23-year-old was expecting a hard match in Nelson.
''They're a tough team and thrashed Counties last week so are going to be on a bit of a roll.
''It was good fun playing for the Ranfurly Shield with such a massive crowd. You don't really notice it, as you are in the zone of playing the game.
''But that is finished with now and we've got to concentrate on this game.''
Tasman will be a tough nut for Otago to crack. The Kieran Keane-coached side has won two of its three games - its only loss was to Canterbury - and looked very impressive in that win over Counties-Manukau last Friday night.
Tasman also has the advantage of having had a full week of rest, and it is the first game in Nelson this year for the team.
Otago was spent after the game against Hawkes Bay last Sunday, both physically and mentally.
It has had a light training load this week and coach Tony Brown has rung the changes to rest some tired bodies.
Otago and Tasman have already played in Nelson this year, in a pre-season match just over a month ago, and the home side won 26-13.
Otago needs to muscle up tonight, show plenty of line speed and kick accurately.
The match will be officiated by Japanese referee Aki Aso, who is having some games in the ITM Cup as part of a commitment by the New Zealand Rugby Union to upskill some promising overseas referees.
Otago v Tasman
Nelson, tonight, 8.05pm
Otago: Buxton Popoali'i, Matt Faddes, Jayden Spence, Peter Breen, Kieran Moffat, Hayden Parker, Fumiaki Tanaka, Paul Grant (captain), Willis Scott, TJ Ioane, Tom Franklin, Charlie O'Connell, Tama Tuirirangi, Sam Anderson-Heather, Craig Millar. Reserves: Liam Coltman, Aki Seuli, Tom Donnelly, Lee Allan, Josh Renton, Tei Walden, Fa'asui Fuatai.
Tasman: Marty Banks, Bryce Heem, Kieron Fonotia, Tom Marshall, James Lowe, Hayden Cripps, Mark Swanepol, Tevita Koloamatangi, Shane Christie (captain), Liam Squire, Joe Wheeler, Alex Ainley, Sila Puafisa, Quentin MacDonald, Tim Perry. Reserves: Francis Smith, Siua Halanukonuka, Tevita Cavubati, Gary Redmond, Billy Guyton, Mitchell Scott, Robbie Malneek.
Referee: Aki Aso (Japan).
