ST. PETERSBURG -- Yandy Díaz is baseball’s best hitter when a game advances into the later, most crucial innings.

Why?

“It seems like moments of tension is when I kind of relax and focus a little bit more,” Díaz said via team interpreter Manny Navarro.

Díaz came off the bench Saturday afternoon to deliver twice when the game’s tension level was as high as the roof at Tropicana Field. He gave Tampa Bay a brief lead with a pinch-hit RBI double in the seventh, then lined a walk-off two-run homer over the wall in right in the ninth to give the Rays a 7-5 win over the Mariners.

• Games remaining: vs. SEA (1), at MIN (3), at BAL (4), vs. LAA (3), vs. TOR (3), at BOS (2), at TOR (3)
• Standings update: The Orioles (90-51) hold a four-game lead over the Rays (87-56) in the AL East. Tampa Bay remains the top AL Wild Card team, the club that gets to host a best-of-three Wild Card Series against the AL’s No. 5 seed, with a 7 1/2-game lead over Seattle and Toronto.

With the victory, the Rays have taken two of the first three games of this series vs. Seattle, the team they would face in a best-of-three AL Wild Card Series at Tropicana Field if the postseason began today. The triumph also represented the Rays’ 12th comeback win over the past month -- the most in MLB -- and their second in as many nights.

“We say the game isn't over until that 27th out is made,” Díaz said. “And for us, we went out there to just try and battle, and we came out on top.”

For most of the afternoon, Díaz was not out on the field, but instead biding his time in the dugout or the home clubhouse. He was out of the starting lineup for the second time this week as manager Kevin Cash just wanted to get the club’s top offensive performer off his feet a little bit.

“But I mean, I can go back in there and change [the lineup],” Cash joked prior to the game.

He would write Díaz's name on the lineup card in the seventh after Taylor Walls tied the game at 4-4 with a one-out RBI single. Díaz began getting ready for his moment by taking a few swings in the batting cage during the sixth inning.

Pinch-hitting for Brandon Lowe, Díaz greeted Mariners reliever Gabe Speier with a double as he pulled a low-and-away slider into the left-center gap, plating Walls.

“That's Yandy,” Walls said. “He’s one of the best hitters I've been around, myself personally, throughout my entire career.”

The Rays’ lead was short-lived, as Robert Stephenson’s first pitch with two outs in the top of the eighth bounced away from catcher René Pinto, allowing Eugenio Suárez to dash home.

With the tension level peaking again in the ninth, Díaz stepped to home plate following a Walls walk with two outs.

Tayler Saucedo’s 1-2 changeup barely nicked the outside corner, but Díaz lashed it at 104.5 mph and watched as the ball landed just beyond the right-field wall for his 19th homer of the season and his first career walk-off dinger.

As he rounded first base, Tampa Bay’s triumphant first baseman flexed his powerful arms.

“He's just such a complete hitter with the power that he's added this year,” Cash said. “The ability, the bat path just stays in the zone so long. He handles good pitching.”

Díaz has handled some of the best stuff from some of the league’s nastiest relievers as he’s piled up big hit after big hit. He is now batting an MLB-best .376 (47-for-125) with 12 extra-base hits, four homers and a 1.020 OPS in the seventh inning or later.

“I didn't know about those stats. I'm not the one that really looks over my stats. … But it’s good to know that those stats are good out there,” Díaz said.

While the day’s hero may be unaware of his knack for hitting in the clutch, his manager and his teammates know what he’s capable of when a game is on the line, especially in a series that has felt like postseason baseball.

“I feel like he's just one of those guys that you just know you can count on,” Walls said.

“He certainly has done MVP things for us,” Cash added.

The Rays will look to clinch this four-game series with a win Sunday before heading out on a huge seven-game road trip. It will first take them to AL Central-leading Minnesota for three games and end with a four-game series in Baltimore that could decide the AL East.

There are destined to be many more high-drama, tension-packed moments for the Rays on the road ahead. And in those moments, the team hopes Díaz will once again have a chance to decide the outcome.

“We probably want him up as much as anybody,” Cash said.