San Francisco Giants' Buster Posey, right, is looked at by home plate umpire Fieldin Culbreth and Arizona Diamondbacks catcher Jeff Mathis after getting hit in the helmet by a fastball thrown by Diamondbacks starting pitcher Taijuan Walker in the first inning of a baseball game Monday, April 10, 2017, in San Francisco. Posey was forced to leave the game. (AP Photo/Eric Risberg)
San Francisco Giants' Buster Posey, right, is looked at by home plate umpire Fieldin Culbreth and Arizona Diamondbacks catcher Jeff Mathis after getting hit in the helmet by a fastball thrown by Diamondbacks starting pitcher Taijuan Walker in the first inning of a baseball game Monday, April 10, 2017, in San Francisco. Posey was forced to leave the game. (AP Photo/Eric Risberg) Credit: Eric Risberg

San Francisco — Giants catcher Buster Posey was doing well after being struck in the helmet by a 94 mph fastball in the first inning and forced out of the game, a frightening moment in San Francisco’s 4-1 victory on Monday against the Arizona Diamondbacks in its home opener.

Posey will be re-evaluated today, but “he’s doing good, he’s doing fine,” manager Bruce Bochy said. Posey is likely to sit out today’s game.

Taijuan Walker’s 0-1 fastball with two out in the first inning sent the Gold Glove catcher immediately to ground. Athletic trainer Dave Groeschner sprinted toward the plate and Bochy was right behind. Posey got up on his own but exited the game, with Nick Hundley entering to pinch run and stay in the game as catcher.

Bochy said if Posey weren’t a catcher, he might have been OK to stay in the game, but the Giants weren’t taking a chance with the 2012 NL MVP and 2010 NL Rookie of the Year.

Walker (1-1) was booed at the conclusion of the inning, when he came up to bat and at every other opportunity by the AT&T Park sellout crowd of 42,129. Home run king Barry Bonds was among those in attendance.

Yankees 8, Rays 1

New York — Michael Pineda retired his first 20 batters before Evan Longoria lined a double down the left-field line, and he wound up pitching two-hit ball over 7⅔ innings in New York’s home opener.

Pineda (1-1) dominated like the pitcher the Yankees have always hoped he would become. He struck out 11, walked none and threw 67 of 93 pitches for strikes. Tampa Bay’s Logan Morrison homered with one out in the eighth, a ball that hit off the top of the wall in right-center and deflected off a fan before bouncing back onto the field. A video review was needed to determine it was a home run.

Alex Cobb (1-1) allowed five runs in 7⅓ innings.

Mariners 6, Astros 0

Seattle — James Paxton shut down Houston for the second time in a week, pitching seven innings of four-hit ball and leading Seattle to a win in its home opener.

The Mariners rebounded nicely from Sunday’s ugly ninth-inning meltdown against the Angels when they gave up seven runs and lost 10-9. Paxton (1-0) was a big reason why, keeping Houston’s offense silent long enough for Seattle’s bats to wake up and finally convert with runners in scoring position. Paxton struck out eight and walked two while pitching in Seattle’s home opener for the second time in his career.

Athletics 2, Royals 0

Kansas City, Mo. — Khris Davis hit a two-run homer, Jharel Cotton shut down Kansas City’s anemic offense and Oakland held on to spoil the Royals’ home opener.

Cotton (1-1) gave up a single in the first and another in the sixth, but otherwise befuddled a Royals lineup that hasn’t shown much punch. He walked three and struck out six over seven innings.

Reds 7, Pirates 1

Pittsburgh — Eugenio Suarez and Scooter Gennett hit solo home runs and Cincinnati pounced on a wild night by Pittsburgh’s Tyler Glasnow.

Glasnow (0-1), making his season debut after locking down the fifth starting spot in spring training, failed to make it out of the second inning as he battled control issues. The right-hander walked five — including four straight in the first — and left after throwing just 35 of his 64 pitches for strikes.

Nationals 14, Cardinals 6

Washington — Bryce Harper tied a career high with four hits and reached base in all six plate appearances as Washington routed St. Louis.

Harper drove in three runs during his first four-hit game since April 17, 2013.

Mets 4, Phillies 3

Philadelphia — Jay Bruce homered twice, including the tiebreaking shot in a testy eighth inning to lead New York over Philadelphia.

Recently bumped up to the cleanup spot, Bruce put the Mets in front 4-2 with a towering, two-run drive off his own digital image on the videoboard in right field on a 1-2 pitch from Joely Rodriguez.

Tempers flared two batters earlier when Phillies reliever Edubray Ramos threw a first-pitch fastball over Asdrubal Cabrera’s head — perhaps seeking revenge for Cabrera’s two-handed bat flip after hitting a game-winning homer against Ramos last Sept. 22.

Cabrera was restrained by Phillies catcher Cameron Rupp, and players from both teams came to the top step of the dugout. Phillies manager Pete Mackanin was ejected by plate umpire Allan Porter, apparently for questioning Porter’s warning to both teams following the pitch.