Fernando Tatis Jr. opened his arms as he trotted up the first base line in the seventh inning Saturday and raised them toward the heavens.

It had been a long time since he’d homered.

Too long.

Far too long.

“It was heavy,” Tatis said after his first homer in 98 plate appearances and 21 games snapped the longest drought of his career and sealed a 5-1 win over the Kansas City Royals. “Everybody knew it. I knew it, how long it was. Just been grinding and trying to put good at-bats together until it happened.”

And he had.

Tatis had reached base at a .383 clip during the 21 games that passed since his last home run on May 27. The Padres went 9-12 during that stretch and have not won a series since June 6-8 in Milwaukee, when his three-run blast in the seventh inning allowed everyone in a sellout crowd of 43,241 at Petco Park to breathe a bit easier.

Dylan Cease’s quality start was that much sturdier. Neither Jason Adam nor Robert Suarez had to be rushed into the game. The relievers that were called upon did not have to sweat a mistake.

And there weren’t many.

Jeremiah Estrada struck out the final batter of the seventh inning and followed Bobby Witt Jr.’s leadoff double in the eighth with a strikeout before passing the baton to Adrián Morejón, who recorded the final five outs without incident to give the Padres a chance to win the series on Sunday.

Even more good news could be on the horizon, too.

Jackson Merrill is eligible to return from the concussion list on Sunday, and after a hearty afternoon of pre-game work on Saturday, Padres manager Mike Shildt did not exactly throw cold water on the possibility.

“We’ve got to get medical clearance for that, and I know Jackson is excited about it,” Shildt said. “(Gavin Sheets was) asking if he’s going to go on a rehab assignment.

“I don’t think that’s going to happen.”

The Padres need all the help they can get — and as soon as they can get it — after beginning Saturday six games off the Dodgers’ pace in the NL West.

After all, they were 12 games over .500 while posting the majors’ eighth-best OPS (.744) through the first 38 games of the season.

Before Saturday’s win, they were 15-22 while posting the majors’ third-worst OPS (.648) since that stretch.

Again, more slug from Tatis will help, which is why everyone breathed a sigh of relief when none of the imaging revealed any breaks in the wrist struck by a pitch in the ninth inning Thursday at Dodger Stadium.

A day later, Tatis was back in the lineup. And on Saturday, he was back to providing some thump.

“Definitely dodged a bullet,” Tatis said while admitting he’s still playing through soreness. “It dodged the bones of my wrist. That’s a delicate area. … Most of the players that get hit in that area, they sit down for a while, but gladly dodged that bullet, and happy I’m still on the field.”

Tatis’ blast came a half-inning after Cease was pushed to 6⅔ innings in just his sixth quality start this season.

Cease had already thrown 102 pitches when he popped out of the dugout to start the seventh inning. He promptly struck out Drew Waters for the first out and got a ground ball that was reversed into an out after a replay showed that Xander Bogaerts’ throw indeed beat John Rave to the base.

That fetched Shildt out of the dugout as Cease raised his right index finger.

“Just letting him know, like, ‘Hey, I got, I got one more if you want it,’” Cease said. “ … Anytime you go deep in general and give the bullpen a break, it’s great. I’m glad he let me do it.”

But a season-high 110 pitches was more than enough.

Cease exited to a standing ovation, Estrada struck out Jonathan India for the final out of the inning and Tatis’ first homer since May 27 provided much-needed breathing room for a taxed bullpen.

Cease allowed his lone run in the third inning when Waters led off with a single and scored on Rave’s ensuing double. He allowed just one other hit in the game, walked three, hit a batter and struck out four.

“Ball was coming out good, was going where he wanted,” Shildt said of sending Cease out for the seventh inning. “He was getting strong. So let’s try to do what we can to take care of our bullpen.”

The Padres had a 2-1 lead in the bottom of the seventh when Jose Iglesias singled for a one-out base runner. Bryce Johnson followed with a single to right, and after a Martín Maldonado strikeout, Tatis yanked a 1-0 sinker over the wall in left on a 108 mph line for a 5-1 lead.

Before that, the Padres scratched and clawed their way to a lead.

Jake Cronenworth plated a run on a ground out in the second inning after Sheets’ leadoff double extended his career-best hitting streak to 12 games.

Luis Arraez’ RBI single in the third gave the Padres a 2-1 lead.

Then, in an instant, the Padres had a 5-1 lead.

For Tatis, it was about time that he reintroduced that phase to his game.

“Take a deep breath and enjoy it,” Tatis said. “It was quick though. Guess I’ve got to do it again.”