ST. PETERSBURG — The Tampa Bay Rays became the first American League team to reach 80 wins this season, routing the San Diego Padres 9-4 at Tropicana Field behind Yandy Díaz’s record-setting night and a five-run fourth inning that featured just two hits.

The victory improved Tampa Bay’s record to 80-54 and ensured the Rays would keep a four-game lead over the Yankees in the AL East with 28 games remaining. Díaz launched his 20th home run of the season in the third inning, an opposite-field shot off Padres right-hander Casey Mize. The solo blast was Díaz’s 119th homer with Tampa Bay, breaking a tie with B.J. Upton for fifth-most in franchise history and pushing Díaz past Carlos Peña into fourth place on the club’s all-time RBI leaderboard.

“It’s a nice time to get going, right?” veteran starter Nick Martinez said. “We’ve earned the spot to play some meaningful games this time of year, and to play against teams that are either already a lock to make the playoffs or fighting to make the playoffs should make for a fun month.”

The Rays sent nine men to the plate in the fourth inning and scored five runs on two hits, with the first two scoring before a ball left the infield. Junior Caminero was hit by a pitch, Chandler Simpson reached on a Mize throwing error, and DeLuca walked to load the bases. Cedric Mullins tapped a ball to first baseman Ty France, who couldn’t cut down Caminero at the plate. Jorge Mateo’s sacrifice fly and Taylor Walls’ RBI single kept the rally going before Díaz capped it with a base hit.

“It’s just chaos, everyone doing something different,” DeLuca said. “You’ve got speed. You’ve got power. You’ve got [guys] just getting on base. … The versatility is, I think, really key to our offense, and we did it well tonight.”

Tampa Bay tacked on runs in each of the next three innings on RBI singles by DeLuca and Caminero and Mullins’ 14th homer of the season. Starter Shane McClanahan earned his 10th win despite surrendering four runs across six innings. “And it’s not just from one person. It’s from everybody,” McClanahan said. “I’m really, really happy that this is my lineup. I can’t say enough good things about the guys.”

The Rays entered the series with the hardest remaining schedule in the AL, based on their opponents’ .513 winning percentage. Tampa Bay faces nine series over the next month, and six are against teams who began the day in position to make the postseason. Simpson said the club is ready. “I feel like all year, the way we’ve been playing, every team is on their heels every inning,” Simpson said. “So just the fact that we were able to execute everything that happened in that inning, I mean, it speaks volumes to that.”

The Rays continue their penultimate homestand at Tropicana Field against the Padres this weekend.