OSAKA, Japan (AP) — Tonga has been conceding heavily without scoring much lately, and the attack has to start firing against Argentina in Saturday's must-win Rugby World Cup match.

Toutai Kefu's squad has scored one try in the past two games. By contrast it has allowed a hatful of them, in a 35-3 World Cup loss to England and a 92-7 thumping by defending champion New Zealand in a pre-tournament warmup.

Kefu is hopeful that Telusa Veainu's return from a foot injury to play at fullback changes the dynamic.

"We don't have many players like Telusa. He is high quality and has a lot of X-factor," Kefu said of the Leicester Tigers player. "He is critical for us. That's why we've thrown him straight in."

Tongan territorial gains counted for little against England, but Veainu could change that.

"I think we were very poor in attack. We didn't execute or throw any punches," said Kefu, a former backrower who won the 1999 World Cup with Australia. "I think he will give us spark in attack, he can make something out of nothing."

Veainu's selection somewhat softens the blow of losing flyhalf Kurt Morath to a throat injury which has ruled him out of the tournament.

James Faiva has the considerable task of replacing Tonga's World Cup and all-time leading scorer, in what will only be his sixth test appearance.

"James' strength is his kicking game and that fits in very well with how we want to play. We want to play territory and keep the ball in front of the forwards," Kefu said. "But he is also going to have to tackle and communicate well."

To help Faiva cope with the defensive demands against a Pumas team which offloads well and has quick backs, Kefu has switched veteran center Siale Piutau from outside to inside center.

"That's where I play for Bristol. Obviously it's a different challenge here, but I will be closer to helping James," said the 33-year-old Piutau, who is making his 10th World Cup appearance. "It will be another physical battle. The scrum and lineout is also our strength and if we can match them (there), I think we will have a good platform."

Argentina has twice finished the Rugby World Cup in third place, in 2015 and 2007.

A defeat would all but end its chances of reaching the knockout stage, however, seeing as Argentina lost its opener against France.

Wales was the last team to fail to reach the knockout rounds in the tournament after playing in the semifinals — exiting at the group stage in 1991 after finishing third in 1987.

Tonga needs to win to keep its own slim chances alive in a hard Pool C, where it still has to play three-time runner-up France.

Although Argentina is favored to win at Hanazono Rugby Stadium, on the outskirts of Osaka, the Tongans believe in a similar upset to Uruguay's 30-27 upset win over Fiji on Wednesday.

"We have seen there is a chance," Piutau said. "Once the stars are aligned, there's a wonderful opportunity for us."

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