SAN FRANCISCO — Mac Williamson remade his swing during the offseason to become a more consistent power hitter. He added a leg kick, lowered his hands, found better balance all in an effort to keep the bat in the zone longer and give himself more room for error.
Whatever he did, it's working. He crushed a ball into the wind.
Williamson hit a two-run homer deep into the right-center field seats in the sixth, Buster Posey had a double and singled in the fifth to put San Francisco ahead, and the Giants beat the Washington Nationals 4-2 on Monday night.
"I just haven't seen many balls hit there even in BP," manager Bruce Bochy said. "With the wind blowing, that's impressive. It shows you how strong this guy is."
Chris Stratton (2-1) struck out five over 6 2/3 innings, allowing two runs and four hits.
Williamson, playing his first home game at AT&T Park this season after being called up during the recent road trip, connected with a deep drive to right-center off Shawn Kelley after he relieved starter Gio Gonzalez (2-2).
"It's a long ways out there. The wind, it's always circling," Williamson said. "I played fair share of games in right so I know that balls don't always go out there very well."
Gonzalez walked Brandon Belt to end his day before Williamson crushed the first pitch he saw from Kelley.
Then, Kelley had to exit the game for what the Nationals said afterward was an irritated ulnar collateral ligament. He has had a history of elbow trouble and will be re-evaluated Tuesday.
"It's another day in the life of my elbow," Kelley said.
The 464-foot shot by Williamson is the furthest homer by the Giants this year, topping his previous 434-foot homer Friday after he was promoted to face the Angels in Anaheim. Earlier Monday, Williamson drove in his team's initial run on a fielder's choice in the fourth.
"That was crushed," Stratton said. "It's nice to see him come up and do well for us. He's provided a spark."
San Francisco kicked off a 10-game homestand by winning back-to-back games for only the second time this season and first since April 4-7. The Giants were coming off their first series victory of the season against the Angels.
The Nationals' runs came on a pair of sacrifice flies, by Howie Kendrick in the third and pinch-hitter Andrew Stevenson in the seventh.
Gonzalez allowed three runs and four hits, struck out four and walked three in five innings.
In his only other start against Washington, Stratton threw 6 2/3 scoreless innings with 10 strikeouts last Aug. 13.
Hunter Strickland, who brawled with Bryce Harper during Washington's last visit to AT&T Park in late May 2017, finished for his fourth save in six chances. Harper didn't bat in the ninth.
Washington traded right-hander A.J. Cole to the New York Yankees for cash. The 26-year-old Cole was 1-1 with a 13.06 ERA in four games for the Nationals and was designated for assignment last week.
Ex-Nationals manager Dusty Baker, who guided Washington to back-to-back NL East titles before his firing after last season, visited the ballpark to see his former club.
Did he plan the visit in advance?
"Maybe," Baker said, grinning.
Nats pitcher Stephen Strasburg hustled out to give Baker a big hug behind the batting cage.
"What's up Dusty, how you doing?" Strasburg said.
Baker also visited with third base coach Bob Henley, the loan holdover from his coaching staff.
Baker is now working in an advisory role to Giants CEO Larry Baer while getting to watch son, Darren, play his freshman college season at California in Berkeley.
"I am good," Baker said. "How bad can it be between Cal, San Francisco and Sacramento?"
Nationals: OF Adam Eaton, on the disabled list retroactive to April 9 with a bone bruise in his left ankle, won't be rushed back until he is completely pain-free. "When you see him in the lineup he'll be ready," manager Dave Martinez said. "He's coming along. When we get him back this time we don't want any issues." ... OF Brian Goodwin remains in Florida with pain in his bruised left wrist.
Giants: LHP Will Smith is eagerly anticipating his return from Tommy John surgery that cost him all of last season, and he could come off the DL as soon as Tuesday. He pitched twice for Class-A San Jose and three times so far for Triple-A Sacramento. He is scheduled to throw consecutive days for Sacramento on Wednesday and Thursday then another short outing Sunday. "We're close. We're getting there," Smith said, noting it will be "awesome. I'm ready to go." ... RHP closer Mark Melancon (flexor strain in pitching elbow) is scheduled to play catch during Thursday's off day. There is no timetable for his return.. ... LF Hunter Pence (sprained right thumb) did some hitting and is scheduled for early batting practice Tuesday.
Giants lefty Ty Blach (1-3, 4.10 ERA) will face the Nationals for the first time in his career when he pitches the middle game of the series opposite right-hander Tanner Roark (1-1, 3.24).