William Contreras launched a walk-off home run in the ninth inning Friday, propelling the Milwaukee Brewers to a 5-4 victory over the visiting San Francisco Giants.

Milwaukee closer Trevor Megill (5-2) allowed a two-out double to Luis Matos and in infield single to pinch hitter Dominic Smith in the top of the ninth before his wild pitch tied the game at 4.

After Randy Rodriguez (3-5) retired Andruw Monasterio and Brice Turang to begin the bottom of the frame, Contreras hit his 14th homer of the season to give the Brewers their major league-high 81st victory and second in a row after a three-game losing streak. Milwaukee starter Jose Quintana allowed two runs on two hits and two walks in 5 1/3 innings.

Willy Adames, who spent the last 3 1/2 seasons with Milwaukee, had a pair of solo homers for the Giants, who dropped their fourth consecutive game. Starter Carson Whisenhunt went four innings, allowing two runs on four hits and two walks.

With the game tied at two in the bottom of the seventh, Giants reliever Joey Lucchesi hit Monasterio with a pitch with one out before allowing Turang's bunt single and Contreras' RBI base hit. After intentionally walking Christian Yelich, Ryan Walker entered for San Francisco, allowing Turang to score on Andrew Vaughn's run-scoring groundout.

Adames then cut the Giants' deficit in half with his second solo homer of the game.

The Giants struck in the first inning as Adames clubbed his 21st home run of the season -- a 419-foot shot against his former team.

Matos' sixth homer of the year doubled San Francisco's lead in the second.

After Yelich singled and Vaughn walked to begin the bottom of the fourth, Sal Frelick lined a double to right, cutting Milwaukee's deficit in half. Whisenhunt's wild pitch brought in the game-tying run two batters later.