Morse broke a sixth-inning tie with his sixth home run of spring training, and the Mariners defeated the Oakland Athletics 6-5 Monday.
Morse homered off starter A.J. Griffin for a 4-3 lead. Morse was reacquired from Washington as part of a three-way deal with Oakland during the offseason.
"Morse has had a good spring for us. He knows what he wants to do. He's smart and strong. That is why he is in the middle of our lineup," Seattle manager Eric Wedge said.
Dustin Ackley had an RBI single later in the inning against Ryan Cook. Ackley, hitting .321, added another run-scoring single in the eighth off Pat Neshek.
"The ball is really coming off his bat. He is spraying the ball around," Wedge said.
Right-hander Hisashi Iwakuma, one of the candidates to become the Mariners' No. 2 spot behind Felix Hernandez, gave up three runs and six hits in five innings, including Derek Norris' two-run homer.
"I thought he threw the ball well," Wedge said. "He was putting the ball on the ground and he used all of his pitches."
Oakland center fielder Coco Crisp leaped and reached over the center-field fence to rob Jesus Montero of what appeared would be a two-run homer in the second.
Griffin gave up five runs and six hits in 5 1-3 innings.
"It went all right. I don't want to make excuses," Griffin said. "The ball really flies here. and we are going to go places where the ball really flies (during the regular season), so I'm going to focus on keeping the ball down and executing my pitches."
NOTES A's closer Grant Balfour, who had right knee surgery on Feb. 14, started a minor league game and threw 17 pitches, giving up two runs and a pair of hits with one strikeout. Melvin said he wants to have Balfour pitch in about five big league games before opening day ... Oakland OF Yoenis Cespedes and INF Hiro Nakajima also were in minor league camp to get extra at-bats. ... INF Eric Sogard had another hit to raise his average to .516 (16 for 31). ... RHP Carson Smith continues to look like a future Seattle closer. He earned the save against Oakland with a strikeout in a hitless ninth and has allowed only two hits and struck out seven in six scoreless innings.