Monty Ioane scored a hat-trick as Benetton Treviso beat defending Pro14 champions Scarlets 22-12 to equal a club-record fourth straight win in the competition.
Both sides were missing a large contingent due to the Six Nations but it was Treviso who coped the better, handing Scarlets their first loss to an Italian team since May 2013.
Ioane benefitted from cross-field kicks from Marty Banks for his opening two scores, the first coming after Johnny McNicholl failed to collect the high ball.
The New Zealander put Treviso 17-0 up early in the second half and Marco Zanon clinched the bonus point, with Corey Baldwin and Tadhg Beirne scores not enough to clinch a losing bonus point.
Scarlets consequently failed to regain top spot in Conference B from Leinster, who moved above them despite a 29-24 loss to Edinburgh on Friday.