ST. PETERSBURG -- During the four seconds after he made contact with Drew VerHagen’s two-strike sinker, Taylor Walls experienced a wave of conflicting emotions.

Off the bat, Walls said he thought he’d hit it “way fair.” As it hooked hard down the right-field line, Walls slowly crept toward first base, leaning his upper body to the left but admittedly thinking, “You’ve got to be kidding me.” But when it bounced off the foul pole and thudded back onto the warning track, Walls reached the end of his emotional roller-coaster ride.

After the Rays were down a run and down to their last strike in the 10th inning, Walls set off a celebration as his first career walk-off homer sent Tampa Bay to a 4-2 win over the Cardinals on Tuesday night at Tropicana Field. It was a gritty victory for the Rays made possible by tremendous pitching, a defensive gem from Kevin Kiermaier and one big swing from Walls.

“They all feel good, but obviously a game like that where it's a battle just kind of shows what this team is made of to everyone else,” said reliever Colin Poche, who picked up the win. “In this clubhouse, we know that we've got a bunch of gritty players who are going to fight to the last strike, and it's exactly what Taylor Walls did tonight.”

Isaac Paredes walked to begin the bottom of the 10th, then Nolan Arenado made a Platinum Glove-caliber play to throw out Kiermaier at third on Brett Phillips’ sacrifice bunt attempt. Pinch-hitter Yandy Díaz popped out to bring up Walls.

The slick-fielding switch-hitter had been in a brutal slump, with only three hits in his previous 25 at-bats. But Walls said he had a conversation earlier in the day with assistant hitting coach Dan DeMent that helped him deliver his first walk-off hit of any kind in the Majors and only his fourth career homer in 99 games with the Rays.

They didn’t talk about swing mechanics or anything too technical. It was more about staying calm in the batter’s box rather than letting the game get too fast, something Walls has struggled with in the past. Not this time.

“The same heartbeat as I would [have], like, playing Wiffle ball -- I mean, that's really what it came down to,” Walls said. “It just happened to play out that I had a big at-bat in a big situation, to where the thoughts just aligned up with the perfect situation today. That was all that was going through my head was, ‘Stay calm, stay composed and just breathe.’”

And what was going through his mind after his first walk-off hit banged off the foul pole? Not much. Before Walls sprinted around the bases, chucked his helmet about as far as he hit the home run and ran into the crowd of teammates around home plate, Rays coach Chris Prieto had to remind him to touch first base.

“I almost ran into the bullpen,” Walls said. “As soon as that ball hit the foul pole, I don't know what happened. … I rounded the bases and I felt like I was sprinting full speed. That moment just was -- I wouldn't say a blur, but it was just in fast forward, I feel like.”

The Rays had to battle just to reach that point, though, on a night their scuffling lineup produced only three hits and three walks. Starter Jeffrey Springs kept the Cardinals’ high-scoring offense in check over six scoreless innings.

The Rays broke a scoreless tie in the seventh on an Isaac Paredes sacrifice fly, but the Cardinals evened it up against Andrew Kittredge in the eighth.

And St. Louis struck first in the 10th, loading the bases with nobody out. But Poche kept his cool even after giving up one run on a sacrifice fly, striking out Tyler O’Neill before Kiermaier delivered the big play Tampa Bay needed to keep the game close.

Harrison Bader hit a single to center, and Paul Goldschmidt dashed home from second to try to extend the Cardinals’ lead. But Kiermaier fired an 83.1 mph strike from center, a one-hop throw just up the first-base line, giving catcher Francisco Mejía enough time to reach across the plate, tag Goldschmidt and end the inning.

“Game-changing,” Rays manager Kevin Cash said. “To get out of that inning … with nobody else [scoring] was just as big as Wallsy's home run.”

Kiermaier was happy to shine the spotlight on Walls, beaming at his locker about his big moment.

“For him to come up huge right there, biggest hit of his career, just incredible,” Kiermaier said. “And it shows you, even when we're having some down times as a team, don't ever count us out. We don't ever give up, and you never know who the hero's going to be on any given night. Tonight was T-Walls' night to be the hero.”