SAN FRANCISCO — Alex Reyes arrived in the majors this year already packing some of the best stuff in baseball.

On Sunday, the 22-year-old Cardinals right-hander showed he can handle the spotlight just fine, too.

Reyes pitched seven dominant innings in his third major league start, fellow rookie Aledmys Diaz hit a two-run homer and St. Louis moved up in the tight NL wild-card race by beating the San Francisco Giants 3-0 on Sunday.

“He kind of answers a lot of questions about whether he can handle pressure when you put him in a spot like that,” Cardinals manager Mike Matheny said. “He knows where we are in the season and he’s been able to stay focused and continue to really maximize the moment.”

The Giants dropped one game behind the New York Mets for the top NL wild-card spot. The Cardinals closed within one game of San Francisco.

St. Louis split this four-game series, winning the final two. The struggling Giants finished their homestand 2-5 and have won just one series at AT&T Park since the All-Star break.

Reyes (3-1) has thrived since being called up on Aug. 9 when Michael Wacha went on the disabled list with shoulder discomfort.

“Coming into the series you know it’s going to be a playoff atmosphere,” Reyes said. “Being on the field for the first time here in San Francisco it was fun and it was exciting to be on the mound.”

Reyes gave up four hits, struck out six and walked two. The righty’s fastball was consistently in the mid-to-upper 90s mph, and he also mixed in a slider.

Not the 100-plus mph stuff he’s flashed, but an efficient game plan that got the job done.

“Just being consistent, throwing everything for strikes and getting early contact and not being afraid to let them put the ball in play,” Reyes said. “That’s what worked today.”

Seung Hwan Oh pitched a scoreless ninth for his 18th save.

Diaz hit his 16th homer in the third off Albert Suarez (3-4). The All-Star’s shot followed Matt Carpenter’s two-out double.

Suarez has allowed three runs or fewer in his first 11 career starts, but the rookie is winless in 10 outings (including six starts) since June 23.

The Giants appeared to still be reeling from another blown ninth-inning lead in Saturday’s 3-2 loss.

“That hurt, not holding on, that’s a big swing,” Giants manager Bruce Bochy said of Saturday’s game.

The Giants were 0 for 6 with runners in scoring position.

“We created some chances today, we just couldn’t get them in, we couldn’t get the big hit,” Bochy said.

LAW AND ORDER

With the Giants in desperate need of bullpen help, manager Bruce Bochy said right-hander Derek Law will be a ninth-inning option in a reshuffling plan going forward. Giants relievers have blown seven of 11 save opportunities this month. The team has already tied a franchise record with eight losses in games it led after eight innings.

Law has an 0.39 ERA in 26 outings since July 4.

“It’s time to tweak it a little bit,” Bochy said, “I’m not saying Law’s the closer, but with him and (right-hander Hunter Strickland), they’re going to be more in the mix in the eighth and ninth.”

TRAINER’S ROOM

Umpires: Plate umpire Brian O’Nora left the game after being struck in the mask by a foul ball of Hunter Pence’s bat in the second inning. He was diagnosed with a concussion by Giants team doctor Kenneth Akizuki. Second base umpire Laz Diaz called the rest of the game behind the plate.

“I’ve been doing this for 30 years and I’ve never been hit that hard,” O’Nora said.

Cardinals: 1B Matt Adams was out of the lineup a day after being pulled from Saturday’s game with a jammed left wrist, but was available to pinch-hit, Cardinals manager Mike Matheny said. … Plans to let injured OF Matt Holliday bat in a simulated game are on hold until further notice. Holliday has been out since Aug. 12 with a swollen right thumb. “We’d like to see consecutive days with him letting it go and no setbacks in order for us to even start talking about having a live session,” Matheny said.

UP NEXT

Cardinals: RHP Carlos Martinez (14-8, 3.15 ERA) pitches the series opener in Colorado. He is 4-1 with six quality starts in his last seven outings.

Giants: LHP Madison Bumgarner (14-9, 2.66 ERA) faces three-time Cy Young Award winner Clayton Kershaw in what will be the 11th matchup between the two southpaws in the series opener in Los Angeles. Bumgarner is 4-3 with a 4.44 ERA in nine starts since Aug. 2.


This story has been updated to correct the spelling of Aledmys Diaz.