Wales looked a little jaded following their energy-sapping win over Rugby World Cup hosts England, but they had enough left in the tank to see off a feisty Fiji side at the Millennium Stadium on Thursday.
Tries from scrum-half Gareth Davies and hooker Scott Baldwin helped Wales record a 23-13 win in a game that threatened to boil over at times.
Vereniki Goneva scored an excellent try for Fiji, who remain pointless after three matches in Pool A.
Wales will be guaranteed a quarter-final place if Australia beat England on Saturday.
However, Warren Gatland’s team will likely need to win their game with Australia on October 10 if England take four points or more at the weekend.