Samoa holding thumbs for injured pivot

Samoa are hopeful influential flyhalf Tusi Pisi will be fit for this week's vital clash with South Africa after he withdrew during the 27-7 win over Fiji.

Assistant coach Brian McLean said Samoa were "optimistic" that Pisi, who kicked 15 points to keep the Sea Eagles' quarterfinal hopes alive, would recover from another flare-up of his hamstring injury.

Pisi, who was included in Samoa's team for Wales only to withdraw at the last minute with the hamstring problem, kicked a drop goal and four penalties but sprayed his last two attempts wide before making way for Jeremy Sua on 64 minutes.

"He was tightening up a bit. We only intended him to play for 60 (minutes) and you can probably tell from his last two shots at goal he'd stiffened up a bit," McLean said.

"But he said he didn't tear it, so we're optimistic in 24 hours his leg will be back to normal."

McLean added that Samoa could "absolutely" pull of the unlikely feat of overturning the world number two side to reach the last eight for only the third time in their history.

"Absolutely we do. We've come into this tournament with a goal and we knew we had to beat either Wales or South Africa and we failed with the first one so we'll be doing everything in our power to beat South Africa," he said.

And beaten Fiji captain Deacon Manu warned that South Africa would have to be at their best to overcome the powerful Samoans at Auckland's North Harbour Stadium on Friday.

"Samoa have got a big ask in front of them but anything's possible in this tournament," Manu said.

"I said they're capable of putting a performance on for the full 80 minutes, they did and they ran Wales pretty close, so anything's possible. South Africa will have to make sure they play their best, their strongest team if they want the victory against Samoa," he warned.