Tunisia's Mohamed Yousri Souguir celebrates victory

The surprise win followed up Tunisia's impressive 21-12 defeat of Australia.

The defeat completed a miserable day for Scotland, who had earlier lost to Australia and New Zealand.

England beat Argentina 26-7 and thrashed Portugal 58-5 to get their campaign back on track after dropping points with a 14-14 draw with Wales.

Mike Friday's England side will face Samoa in Saturday's quarter-finals, while Wales will face Fiji.

"The boys really seemed to learn from their early mistakes and nerves in the Wales game, and it appears that the penny is dropping in their understanding of their running lines on and off the ball," said Friday.

"The spirit and effort that the players displayed certainly bodes well for a difficult quarter-final against Samoa."

Wales, who scored a last-minute try through Tal Salley to draw with England, battled to a narrow 10-7 win over Argentina and a 17-5 defeat of Portugal.

New Zealand ended the first day with three wins out of three after beating Scotland, Tunisia and Australia.

Fiji also laid down a marker, backing up a hard-fought 22-14 win over Canada by beating Zimbabwe 47-7 and Samoa 45-5.

Tunisia's reward for their two wins is a quarter-final meeting with unbeaten South Africa.