Samoa recovered from a 10-point deficit to beat Italy 33-25 in a sweltering test in Apia on Friday.
The home side scored four tries to three in a successful start to the tenure of new coach Mahonri Schwalger and newly appointed captain Theo McFarland.
Italy were favoured to win, coming off an encouraging Six Nations campaign in which they beat Wales and Scotland.
Coach Gonzalo Quesada fielded an Italian team at close to full strength, and they led 25-15 early in the second half before falling away in hot, humid conditions over the final 30 minutes.
Samoa surged home through late tries to backs Danny Toala and Afa Moleli, along with accurate goalkicking from fly-half D'Angelo Leuila, who landed five of his six shots at goal and tallied 13 points.
Italy led 18-12 at halftime through tries from wingers Monty Ioane and Louis Lynagh in response to Samoan five-pointers to debut flanker Murphy Taramai and winger Nigel Ah Wong.
Fly-half Paolo Garbisi scored 15 points for Italy, including an opportunistic try soon after the interval.
Italy's remaining tour games are against Tonga in Nuku'alofa next week, followed by Japan in Tokyo.
Samoa hadn't played since failing to advance through their group at last year's World Cup.
They will play Spain in Apia next week.