The Mariners didn't just knock off Boston. They thumped their way past the Red Sox and their ace, Chris Sale.
Beckham hit two of Seattle's three home runs off Sale, and the Mariners improved to 3-0 with a 12-4 victory in their home opener Thursday.
The Mariners followed up their two wins over Oakland last week in Japan by rattling Sale (0-1) and knocking out the lefty that had dominated Seattle in the past. Sale was done after just three innings, while the Mariners were just getting started on their big offensive day.
"We like our team. It's a different look to our team. I get that. It's not the household names, the names you are used to seeing in our lineup," Seattle manager Scott Servais said. "But these guys can play and I've said it all along, as this season goes along I think fans will have plenty of guys to latch onto because we certainly have personality on this team. You saw some of that come out today."
Beckham did the most damage, hitting a solo homer in the second and following up in the third with a two-run shot to center field. The infielder was hitless in 15 career at-bats with nine strikeouts against Sale before hitting his second and third home runs of the season.
"I know the past history. I don't care about that," Beckham said. "He still has to come out and throw the ball. I respect him -- he's a really good pitcher. I wanted to see something up in the zone I could handle. ... He normally gets me with the fastball up. I was looking for the one up and I got a good pitch to hit."
Santana has nine RBI in three games, the most in team history after the first three games of a season. He had 20 RBI in 85 games last year with Milwaukee.
Sale had overpowered Seattle the last three times he faced the Mariners, with double-digit strikeouts in all three outings. And it appeared he was headed for another dominant performance that would have delighted the numerous red-clad fans that showed up at T-Mobile Park to see the World Series champs. Sale struck out the side with ease in the first inning.
His opening day outing fell apart quickly from there.
"It's 2-0 and I'm going out there in the second inning, and I pretty much deflated us," Sale said. "Three runs, it's a one-run ballgame, anything can happen and I just go out there and stink the place up. That's not what I needed to do."
Beckham's homer started Sale's problems, but it was his inability to finish off the second inning that raised his pitch count and led to two runs. Sale issued a two-out walk to David Freitas, gave up a single to Dee Gordon and hit Mitch Haniger with a pitch to load the bases.
Santana drove in a pair with a double into the right-field corner, and further damage was averted when Haniger was thrown out at the plate. But Sale was already on a limited pitch count and was pulled after giving up four more runs in the third and reaching 76 pitches.
Boston manager Alex Cora singled out Santana's double as a key at-bat.
"Today was not a good one. Sometimes you make mistakes and they miss it, but they didn't," Cora said. "The double down the line, that was a tough one."
Seattle starter Marco Gonzales (2-0) was shaky early, but pitched into the sixth and allowed three earned runs. Boston had nine hits off Gonzales, but very little solid contact until the sixth inning when doubles by Eduardo Nunez and Christian Vazquez led to a pair of runs and ended Gonzales' day.
Gonzales, who went to Gonzaga, was thrilled to learn almost immediately after being pulled in the sixth that his school's basketball team had beaten Florida State to advance in the NCAA Tournament.
BELT IT LIKE BECKHAM
Beckham became the first player to hit two home runs in a game off Sale since Josh Donaldson on Sept. 26, 2017. Beckham had his fourth two-homer game and first since May 4, 2017, vs. Miami when both homers came off Dan Straily.
Beckham has reached base in 10 of his 14 plate appearances.
Seattle is 3-0 for the fourth time in franchise history. The team's only 4-0 start came in 1985 when the Mariners won their first six games.
Red Sox: Cora remained uncertain whether Steve Pearce (calf) will be ready to join the club later in the road trip when his stint on the injured list is up. Pearce did not play at extended spring training Thursday but was expected to get at-bats on Friday. ... Dustin Pedroia (left knee) went 1 for 4 as the DH at extended spring. Cora said the club needs to see how Pedroia reacts to playing on a daily basis before having conversations about his next move.
Red Sox: RHP Nathan Eovaldi (6-7, 3.81 ERA) went 5-4 in 18 appearances last season after being acquired by Boston, including the postseason.
Mariners: LHP Yusei Kikuchi (0-0) will make his anticipated home debut for Seattle. Kikuchi threw 4 2/3 innings during the team's second game in Tokyo, allowing one earned run.
More AP MLB: https://apnews.com/MLB and https://twitter.com/AP-Sports
Real or not? The Red Sox's bullpen could be their fatal flaw
With another blown save, Boston's late-game issues aren't going away. It's time for Dave Dombrowski to make a bold move.
Riley 'fortunate' his first hit was a homer
Austin Riley talks with Scott Van Pelt to discuss how it feels to be in the MLB, celebrating his debut with his family and how he fits in with the Braves.
Keuchel gets 1st win with Braves in 5-3 victory over Cubs
Dallas Keuchel earned his first win for the Atlanta Braves and Nick Markakis hit a three-run homer Wednesday night in a 5-3 victory over the Chicago Cubs.
Bell, Dickerson lead Pirates to 14-2 rout of Astros
Josh Bell hit his 21st homer, Corey Dickerson had four hits and three RBI, and rookie Dario Agrazal threw six strong innings to earn his first major league win as the Pittsburgh Pirates routed the Houston Astros 14-2 on Wednesday night.
Mariners top Brewers 4-2 for 3rd straight win
J.P. Crawford drove in three runs and Wade LeBlanc struck out six in five innings and the Seattle Mariners extended their winning streak to three games with a 4-2 victory over the Milwaukee Brewers on Wednesday night.
Pirates blast 4 HR's in rout of Astros
Josh Bell, Jung Ho Kang, Jose Osuna and Kevin Newman all connect on home runs to help the Pirates handle the Astros 14-2.