Right-hander Kevin Gausman pitched like an All-Star and Curt Casali provided a three-run home run Sunday afternoon, sending the host San Francisco Giants to a three-game sweep of the Washington Nationals with a 3-1 victory.

The National League West-leading Giants finished the first half at 57-32, giving them the most wins in the majors and the highest winning percentage (.640).

The 57 wins equals the third-most in franchise history at the All-Star break, trailing only the 59 wins in 1993.

Gausman (9-3) snapped a personal two-game losing streak, allowing one run on four hits over six-plus innings with three walks and nine strikeouts.

Selected to the NL All-Star team, the first-year Giants pitcher will not participate in Tuesday's All-Star Game on short rest, but remains on schedule to open the club's second half Friday at St. Louis.

Gausman pitched with a lead most of the way as the result of Casali's home run in the second inning. All-Star Brandon Crawford led off the second with a single and one out later, advanced a base on an infield hit by Steven Duggar.

Casali, who had no home runs in his first 29 games for the Giants, then belted his fourth homer in his last 12 outings, a 420-foot blast to center field off Nationals right-hander Erick Fedde (4-6).

They were the only runs the Giants got off Fedde, who worked five innings and allowed eight hits and three walks. He struck out seven.

The Nationals got back within 3-1 on a bases-loaded fielder's-choice grounder out by Josh Harrison in the seventh. Right-hander Dominic Leone ended the threat, getting Ryan Zimmerman to fly out to shallow center field before striking out Victor Robles.

Set-up man Tyler Rogers threw a 1-2-3 eighth for his 17th hold before closer Jake McGee worked around a two-out double by Starlin Castro in a scoreless ninth for his 19th save.

Crawford went 3-for-4 and Mike Yastrzemski added two hits for the Giants, who won their fourth consecutive game.

Castro collected three of Washington's five hits in the loss.

--Field Level Media