Scotland will need Tonga to draw with or beat Italy on Sunday if they are to progress to the quarter finals of the World Cup.
Tonga can no longer qualify from Group and Scotland have the same points difference as the Italians ahead of the final game of the group.
The Scots scored four unanswered tries in the second half to take this contest with Alex Hurst, who had been near on numerous earlier occasions, finally crossing a minute from time.
Brett Phillips opened their scoring eleven minutes after the break, and man of the match Matthew Russell cut back inside three minutes to add to their tally.
Luke Douglas charged over from a tap penalty on 63 minutes and although the contest got heated towards the end the Scots finished with Danny Brough’s long ball sending Hurst in for a deserved try.