SAN DIEGO -- On paper, the contest Thursday at Petco Park was akin to a playoff game: two teams with realistic October aspirations clashing for the first time this season. The result was a tense evening that carried all the intrigue of various managerial decisions, superstars making plays, and late-inning drama.

On this night, the Mets fell short, dropping a 4-3 game to the Padres. But it easily could have gone the other way, prompting manager Luis Rojas to bemoan: “We created our chances. … For us to create those situations and not to come through with the big, big hit, it’s another tough one.”

• Box score

Here are three of the moments that mattered most -- and hurt most -- from the Mets’ series-opening loss in San Diego:

In-N-Out homer
Of particular intrigue pregame was the status of San Diego shortstop Fernando Tatis Jr., who had sat out Wednesday because of midsection tightness and was no guarantee to play against the Mets. About an hour before first pitch, the Padres finally revealed their lineup, with Tatis in it.

Doubting Tatis’ readiness would have been foolhardy. In his second at-bat, he sent a deep fly ball to center, where Mason Williams timed his leap and snared the ball in his glove -- but only for the briefest of moments. Before Williams could squeeze it, the ball popped out, hit the top of the fence and rolled over it for a two-run homer.

“It just came out of my glove when I impacted the wall,” Williams said. “It’s a play I probably should make.”

That was not the last the Mets would see of Tatis, who later dashed home with the Padres’ fourth run on a wild pitch that did not bounce far from home plate.

“There’s probably maybe a handful of guys who are going to take that chance, and it's less than that who are actually going to be safe,” said Mets pitcher Taijuan Walker, who hustled to cover home plate to no avail. “And he’s one of those guys.”

Pushing the Pete button
As the middle innings of the game unfolded, Rojas faced one decision more important than all others: when to push the Pete Alonso button.

Alonso did not start the game because the Mets wanted to give him rest following his recent return from the injured list with a sprained right hand. But Rojas noted beforehand that “in the National League, you don’t get days off,” intimating that Alonso would hit at some point. The only question was when.

Due in part to the status of his taxed bullpen, Rojas passed on an opportunity in the top of the fifth inning, when Walker’s spot came up with runners on the corners and two outs. In a three-run game, Walker grounded out, and the rally died.

If that decision seemed questionable at the time, it proved prescient an inning later, when the Mets loaded the bases with one out with reliever Tim Hill pitching for San Diego. Rojas responded to the even juicier situation – the Mets trailed, 4-2, after James McCann’s two-run home run – by calling on Alonso, who promptly grounded into an inning-ending double play.

The manager then removed Alonso from the game, which prevented him from making a late impact but was also part of the deal: The Mets wanted this to be something close to a true off-day for Alonso in his first week back from the IL.

“It was the agreement of just trying to keep him off his feet a little bit,” Rojas said.

Stop right there
The Mets’ next-best chance to complete a comeback against the Padres unfolded in the eighth inning, with Francisco Lindor on first base and two outs. Facing reliever Emilio Pagán, Billy McKinney hit a booming fly ball to the right-field corner, where it bounced around as third baseman Manny Machado -- shifted into the outfield -- raced all the way out to the fence to corral it.

While this was happening, McKinney sprinted around second and made a wide turn toward home, but third-base coach Gary DiSarcina threw up his hands to stop McKinney from attempting to score. It likely would have been an extremely close play at the plate, which -- with two outs in the eighth inning of a one-run game -- would have fit with the aggressive style that Rojas espouses.

“We always want to be aggressive,” Rojas said. “Coaching third base is hard -- it’s a hard job. You’ve got to anticipate. You’ve got to see the play unfold. … A lot of times, you want to take a chance, because they’ve still got to make a perfect throw to home, and they’ve got to make a tag, and there are going to happen. But I’m going to stick to my third-base coach’s decision. I think he probably would have been out at home plate.”

Rojas added that he prefers aggression in general -- just not in this instance.

“We’re just fortunate, two things -- that ball stayed in the ballpark and Manny finished the play,” added Padres manager Jayce Tingler. “Because we could still be playing right now if not.”