The Trojans (7-9) have now dropped six of seven after winning six of their previous seven.
USC held a 3-1 lead after four innings. AJ Ramirez had a two-run double in the second inning and James Roberts had an RBI double in the fourth, but Pepperdine (8-8) scored eight runs over the next three innings.
The Waves struck for five of those runs in the sixth inning. Yamaguchi hit a two-run homer that stayed inside the right field foul pole to put the Waves ahead 5-3. They loaded the bases with a single, hit by pitch and walk for Bryan Langlois, who cleared the bases with a double over the right fielder.
Yamaguchi added a deep solo shot to the left of the scoreboard in right-centerfield — an area of the ballpark where few home runs are typically hit — the following inning.
Mat Snider picked up the win with three innings of one-run relief for starter Jackson McClelland. Langlois finished with three hits and four RBI while Yamaguchi had two hits and three RBI.
Check out the 16-shot photo gallery from Tuesday night’s matchup: