Steven Rios was so fired up for Wednesday’s clash with Oakdale that he could feel his body tightening up in the batter’s box.

The hard-hitting third baseman calmed himself in time to vault short-handed Sierra into a lead all its own in the Valley Oak League title chase.

Rios slapped a bases-clearing double down the right field in the fifth inning and diminutive ace Leo Soto finished with a flurry of strikeouts as the Timberwolves opened this pivotal series with a 4-2 victory.

Sierra was playing without third-year standout and starting catcher Jake Souza, who suffered a concussion in practice and will miss Friday’s game.

The Timberwolves (8-1, 14-4-1) now hold a one-game lead on the Mustangs (7-2, 11-8).

“This was a huge win for us for a couple of reasons,” Sierra coach Jack Thomson said. “One, we’re at home. When you play a team like Oakdale, you like to think you can (beat) them at home. They’ll be tough to beat there. Second, those last four innings, that was the Leo from last year. We haven’t seen that a lot.

“And the other thing is we’re banged up. ... I thought it was a great win for that reason, too.”

Sierra trailed 2-1, but rallied into the lead with a three-run fifth inning. Anthony Arredondo, Souza’s replacement, led off the frame with a walk and lead-off hitter Ryan Vasquez was plunked in the thigh one batter later, forcing Oakdale coach Nathan Gregory to pull his starter, Tanner Emes.

There was little relief in the bullpen.

A walk to Nick Oseguera loaded the bases for Rios (2 for 3), who just missed on a home run down the left-field line in the fourth inning.

The junior made the correction, shaking off the nerves and simplifying his approach. He went with a pitch from Ryan Poff, roping it down the right-field line. The ball landed just inside the foul line, sending the Timberwolves racing around the bases.

Arredondo and Vasquez scored with ease. Oseguera raced home on a throwing error.

“I put a lot of pressure on myself and tried to loosen up at the plate; tried not to do too much,” Rios said of the double. “I was a little tight early.”

Staked to a two-run lead, Soto summoned his best stuff — a looping breaking ball that paired nicely with a sneaky fastball.

The senior retired the final nine batters of the game, including four on strikes, for his third complete game of the season.

Soto, who gave two runs on six hits, is now 6-3 with an ERA south of 2.00.

Oakdale made life difficult on the left-hander early, though. The Mustangs’ lead-off batter reached base in three of the first five innings, and Oakdale loaded the bases with no outs in the second.

Soto escaped that jam by inducing two pop-ups. He closed the inning by throwing a fastball, high and tight, by the Mustangs’ Logan Hall.

Oakdale would capitalize in the third inning. Nolen Legan (2 for 3, stolen base) led off with a single and moved into scoring position on Bryce Kirk’s double over Jakob Gallagher’s glove in left field. Both would score on grounders to short to make it 2-1.

The gap could have — and probably should have — been wider for the Mustangs, whose two-game win streak was snapped. Oakdale was 1 for 11 with runners in scoring position and stranded six.

“He made some big pitches,” Thomson said of Soto. “He gives us a chance because he pitches to contact and he locates easily.”

Sierra’s Nick Lucchetti drove in the game’s first run with a triple into the right-center gap, scoring Rios. Gallagher was thrown out at the plate.

Thomson said it’s no coincidence Sierra scored all of its run on opposite-field hits. They’ve honed that kind of plate discipline in practice.

“We work a lot on hitting the ball the other way,” he added.

The Timberwolves go hunting for the series sweep on Friday in Oakdale with emerging starting pitcher Gallagher, who tossed a five-inning no-hitter against Kimball last week.

“We still have another game to handle,” Rios said. “We’ll approach it how we took it today.”