The struggling Lotte Marines toppled Pacific League-leading Rakuten Eagles 6-4 Tuesday behind six shutout innings from Taiwan lefty Chen Kuan-yu, making his first start of the season.

Chen, who went 5-4 in 2015 and 1-1 last year, had thrown three innings of relief over two games this year with one earned run. But he kept in-form Rakuten at bay at Kobo Park Miyagi, scattering three hits in an effective 120-pitch effort, issuing five walks and fanning none.

"I hadn't pitched deep into a game before today...(but) I could get them out thanks to (good game-calling by catcher Tatsuhiro) Tamura," Chen said after Lotte improved to 9-21 with one tie.

Chen's opposite number, lefty Wataru Karashima (3-2), had won his first three starts but has now lost two straight. He lasted only 3-2/3 innings, while surrendering five runs on six hits. It was only the second time this season a Rakuten starter has failed to go at least four innings.

Lotte's Kei Hosoya struck out three times but his only hit came at the right time, his two-out, two-run triple plating Taiga Hirasawa and Shota Ishimine to open the scoring.

Karashima got two quick outs in the fourth, but fell behind in the count to Tamura and Hirasawa, who hit back-to-back singles. Takashi Ogino doubled in both and scored on Ishimine's RBI triple to knock out Karashima, who struck out one and issued three walks.

Matt Duffy's solo shot in the sixth off reliever Kenji Tomura made it a six-run game for the Marines but the Eagles, who entered the game with a 20-7 record, didn't go away without a fight before a home crowd of 25,451.

Eigoro Mogi hit a one-out solo shot off reliever Tomohito Sakai in the sixth. With two on right fielder Ikuhiro Kiyota caught a Zelous Wheeler drive high off the fence above the outfield wall to save two runs.

Ginji Akaminai singled in a run for the Eagles in the inning, and Hiroaki Shimauchi singled and scored on a groundout in the eighth. Tatsuya Uchi wrapped up his second save after surrendering a huge solo homer to Wheeler with one out.