SAN FRANCISCO -- An opportunity awaited the Padres in San Francisco this weekend. There are six other teams currently in the National League playoff picture, and those six teams were all playing series against each other elsewhere.

Which gave the Padres this assurance: If they won, they knew they’d gain ground on ... somebody.

As it turned out, they gained ground on everybody.

San Diego completed a tremendously important sweep of the Giants with a 4-3 victory in 10 innings on Sunday afternoon at Oracle Park. The win moved them 20 games above .500 for the first time since 2010.

“It was huge,” Fernando Tatis Jr. said of the sweep. “Especially with how close the standings are right now. This team is on a mission, and we definitely want to get there. This is what it takes.”

Tatis’ eighth-inning homer -- the first of his career as a pinch-hitter -- put the Padres on top. In the ninth, closer Robert Suarez endured his second blown save in three attempts. But San Diego pulled ahead for good with a two-run rally in the 10th, improving to 9-1 in extra-innings this season (after a dreadful 2-12 mark a year ago).

“When you get into close games, it’s about execution,” said manager Mike Shildt.

With the win, San Diego remained 3 1/2 games back of the Dodgers in the National League West race after Los Angeles beat the Braves on Sunday Night Baseball.

In fact, the Padres emerged from their weekend series closer to the top of the division than the cut line. Their sweep moved them 3 1/2 games ahead of the Mets, currently the first team on the outside of the playoff picture.

The Padres also picked up two games on the Diamondbacks, who narrowly avoided a sweep with a 10-inning win over Milwaukee on Sunday. San Diego leads the race for the top Wild Card spot by 1 1/2 games over Arizona. It’s a lot to take in.

“There’s other teams close to us,” Tatis said. “Obviously we want to win every single game. But if you’re into baseball -- and this group loves the game -- everybody’s paying attention.”

Tatis was out of the starting lineup Sunday, another planned off-day as part of his return to action following an extended absence due to a stress reaction in his right leg. The Padres would prefer to avoid using Tatis at all on those off-days. (After his pinch-hit at-bat, they didn’t play the Platinum Glover in right field.)

But with the game tied at 1 in the eighth, the situation clearly called for Tatis. He wasted no time, launching the first pitch into the left-center-field seats for his first career pinch-hit home run.

“I was going to be ready no matter what,” Tatis said.

The Padres, who got five-plus innings of one-run ball from lefty starter Martín Pérez, carried a 2-1 lead into the ninth. That’s when Suarez -- who had blown only two saves in the ninth inning across the season’s first five months -- endured his second in three outings.

Ten days ago, Suarez put three men aboard, then surrendered a go-ahead grand slam to the Tigers’ Parker Meadows. He wasn’t nearly as shaky on Sunday. But Giants left fielder Heliot Ramos hit an opposite-field home run on Suarez’s 100.2-mph fastball, tying the game at 2.

The Padres, of course, have plenty of closer candidates in their loaded bullpen. But Shildt left no doubt after the game that Suarez remains his guy.

“I will take him tomorrow in a one-run game, I’ll tell you that,” Shildt said.

As they have all season, the Padres responded. David Peralta singled home the go-ahead run in the 10th. Luis Arraez -- who extended his streak without a strikeout to 140 plate appearances -- hit an opposite-field double. That moved Peralta to third, before he scored on Donovan Solano’s RBI groundout.

The Padres brought a two-run lead to the bottom of the 10th inning, where they flaunted their embarrassment of riches in the bullpen. They’d already used their four highest-leverage arms. And yet, they still had Adrian Morejon -- who owns a 3.00 ERA and a 2.86 FIP across 60 innings this season -- for the 10th. Morejon nailed down his second career save.

“It feels great to be a part of this bullpen,” Morejon said through interpreter Pedro Gutierrez. “… We have a chance to give the team an opportunity to win every single day.”