Koki Yamaguchi hit a grand slam to back pitching sensation Roki Sasaki as the Chiba Lotte Marines held on for a 6-5 win over the Hiroshima Carp in an interleague game Sunday.

Sasaki (5-1) struck out 10 in seven innings, allowing two runs on five hits and walking one at Zozo Marine Stadium in Chiba. The 21-year-old right-hander left with a four-run lead, and his fastball clocked as high as 165 kilometers (102.5 miles) per hour.

Yamaguchi's grand slam off Takumi Kurohara (0-1) put the Pacific League-leading Marines up 4-0 in the third. Katsuya Kakunaka added a two-run double for Lotte two innings later.

Sasaki retired the first 12 batters he faced before the Central League's Carp loaded the bases in the fifth with a pair of hits and a walk, setting the stage for Ryutaro Hatsuki's two-run single, his first hit of the season.

"I was able to pitch under less pressure after Yamaguchi-san's grand slam," said Sasaki, who told his coaching staff he would pitch one more inning after the sixth. "Our lead shrank as I gave up runs, so I wanted to work through long innings and hand the baton to the bullpen."

Marines closer Naoya Masuda got in and out of a bases-loaded, one-out jam in the ninth for his 16th save.

In other action, Tomoyuki Sugano (1-0) allowed two runs in five innings in his season debut as the Yomiuri Giants beat the Fukuoka SoftBank Hawks 4-2. The CL-leading Hanshin Tigers blanked the Hokkaido Nippon Ham Fighters 1-0.

The Tokyo Yakult Swallows beat the Seibu Lions 3-2, while the Yokohama DeNA BayStars defeated the Orix Buffaloes 8-4.