It was a debut to forget for Julian Merryweather on Sunday afternoon at Canal Park.

Merryweather, the newest member of the RubberDucks’ starting rotation, received a rude welcome to the Double-A level, and the Ducks suffered a 12-2 setback to the Trenton Thunder, losing three of four in the weekend series before 7,021 fans.

And for the first time all season, the Ducks (43-34) find themselves out of first place in the Eastern League’s Western Division, one-half game behind the Altoona Curve (42-32), a 5-2 winner over Bowie on Sunday.

The Ducks start a seven-game road trip in Richmond at 6:35 p.m. Monday.

Merryweather was promoted from High-A Lynchburg, where he was 8-2 with a Carolina League best 1.03 earned run average in 11 starts.

But he struggled through his worst game of the season, departing after allowing a seven-run fourth inning and nine runs — all earned — on 10 hits.

The 6-foot-4, 200-pound 24-year-old right-hander vowed to learn and improve from the experience.

“Not getting ahead of guys like I usually do,” he said. “No matter what level, pitching like that you’re not going to have a lot of success. Falling behind in counts, not getting my off-speed over so basically they’re just sitting fastball.”

Ducks manager David Wallace acknowledged Merryweather might have been adversely affected by the moment.

“First start in Double-A I think he’s a little excited, obviously, as he should be,” said Wallace. “Wasn’t able to drive his fastball down in the zone. It was up a good bit. Off-speed was a little inconsistent.

“But just seeing the stuff, and how he kept his composure for a rough outing for him, I’m actually pretty encouraged and excited to see how he bounces back. He’ll pitch well for us.”

Trenton catcher Kyle Higashioka hit two three-run home runs (his fifth and sixth), one in the fourth and another in the ninth against reliever Nick Maronde, and a run-scoring double in a two-run first. He went 3-for-5 with seven RBI.

The Thunder collected seven hits in the fourth including Jose Rosario’s two-run triple and Michael O’Neill’s first home run, a two-run shot.

“I think there is a lot to learn,” said Merryweather. “It would be silly of me not to try and learn from this, having a bad outing. Really gets me back on the drawing board, what I need to work on. I’ll take this as a big opportunity to get better and try to improve for next time.”

The only runs for the Ducks were provided by Clint Frazier’s two-run home run to left off reliever Nestor Cortes in the sixth, his ninth of the season, Trenton left-hander Carlos Smith (1-2) allowed two hits, striking out five, in five scoreless innings.

Frazier, a left fielder, is 10-for-31 with two homers in eight games since June 19, though just 2-for-15 the last three. The Indians’ 2013 first-round draft pick (fifth overall) is hitting .295 in his first year at Double-A.

“Just trying to be as consistent as I can,” said Frazier. “Making sure that I trust what I’m doing in the [batting] cage and on the field before each game. Just preparing myself for the upcoming game. I feel good at the plate. The results don’t say that this series, but I felt good up there and just didn’t get the hits I wanted.”

The Ducks made several player moves Sunday. Infielder Claudio Bautista and catcher Daniel Salters were promoted from Lynchburg to Akron, while catcher Alex Monsalve, outfielder Luigi Rodriguez and pitcher Nick Pasquale were sent to Lynchburg. Infielder Angel Miguel heads to Low-A Lake County.