A show-stopping play in the field set the stage for a dramatic finish as the Swallows' Aaron Guiel lowered the curtain on the BayStars with a sayonara home run.
Moments after second baseman Hiroyasu Tanaka's prevented Yokohama from taking the lead in the top of the ninth at Jingu Stadium, Guiel homered with a man on to lift Tokyo Yakult to a 4-2 victory.
Despite their relative lofty placing in the Central League standings, the second-place Swallows snapped a five-game losing skid to the cellar-dwelling BayStars.
With one out and runners on the corners in a game tied 2-2 in the top of the ninth, Yokohama's power-hitting leadoff man Yuki Yoshimura lined one between first and second off closer Lim Chang Yong (3-0).
"I saw it wasn't dropping so I made up my mind to get it," Tanaka said. "If it hadn't been Yoshimura, I would have played shallower and probably wouldn't have had a chance.
"I had an image of myself making the catch. It wasn't easy but I thought I could make it. It turned out the way I imagined."
Tanaka leaped and caught it in his outstretched glove. The runner from first, who assumed like most everyone else in the park that the ball would get through, was doubled off with a casual flip to first.
The play kept Lim's ERA at zero and set the stage for Guiel's final act.
BayStars right-hander Hiroki Sanada (2-2) came on in the bottom of the ninth and gave up a leadoff single to Jamie D'Antona. Guiel then crushed a hanging 2-2 forkball into the right-field stands to end it.
"It was a forkball that hung. It was a mistake and I was able to capitalize on it," Guiel said of his 14th homer of the year and his second in two games. "I was able to keep my hands back and recognize it was a mistake."
The BayStars had grabbed the early lead with a run in the first off right-hander Ryo Kawashima.
Kazuya Fujita singled with one out, stole second and scored on Shuichi Murata's two-out single.
The Swallows did their guests one better in the home half against BayStars ace Daisuke Miura. A leadoff walk, a sacrifice and a single by Kazuki Fukuchi tied it. Fukuchi went to third on a single and scored on Guiel's sacrifice fly.
The BayStars, who gave away a two-out, bases-loaded chance in the sixth when a runner was picked off to end the inning, tied it in the top of the seventh.
Right-hander Kenichi Matsuoka issued a leadoff walk and paid the price. After the compulsory sacrifice, Yoshimura singled home speedster Takehiro Ishikawa from second.
Although the game was marred by base running lapses on both sides, the fielding was on the money.
Yoshimura made a good play against the wall in right field to keep the Swallows from widening their lead in the third, while shortstop Ishikawa started a double play with a diving stop in the fourth after Miura walked Guiel to open the inning.
Miura, who was 2-0 with one run allowed in his two other starts against Yakult, went seven innings, allowing two runs on four hits with four walks and four strikeouts.
"Miura's always tough on us," Guiel said. "He doesn't make many mistakes, so you have to have a good plan and really concentrate."