SAN FRANCISCO (Interstat) — Javier Assad pitched six scoreless innings and Michael Busch hit a three-run homer in the fifth inning as the Chicago Cubs defeated the San Francisco Giants 5-1 on Friday night at Oracle Park.

Assad allowed three hits, struck out five and walked none in his second consecutive strong outing against the Giants. The right-hander, who threw 6 1/3 scoreless innings against San Francisco on June 7, improved to 4-1 on the season. He lowered his ERA to 2.01 with the performance.

The Cubs snapped a two-game losing streak and improved to 36-34, while the Giants dropped to 28-42 with their third straight loss.

Chicago broke a scoreless tie in the fourth inning against Giants starter Landen Roupp. Michael Busch led off with a walk, then Ian Happ grounded into a forceout that erased Busch at second. Seiya Suzuki followed with a sharp line-drive double to center field, scoring Happ and advancing to third. Nico Hoerner then lifted a sacrifice fly to left, bringing home Suzuki to make it 2-0.

The Cubs broke the game open in the fifth. Carson Kelly walked to lead off the inning, and after two outs, Alex Bregman doubled to center, sending Kelly to third. Busch then crushed a fly ball to right field for his eighth home run of the season, clearing the bases and giving Chicago a 5-0 lead.

Roupp took the loss, falling to 5-7. He allowed four earned runs on four hits over 4 2/3 innings, striking out five and walking two.

The Giants’ offense struggled to mount any threat against Assad. Luis Arraez singled in the first inning and Bryce Eldridge singled in the fourth, but San Francisco did not advance a runner past second base until the sixth. In that inning, Eldridge reached on a single and moved to second on a throwing error by second baseman Nico Hoerner, but Casey Schmitt popped out to end the inning.

Trent Thornton worked the seventh and eighth innings for the Cubs, allowing one earned run on one hit while striking out two. Hoby Milner pitched a perfect ninth.

San Francisco avoided the shutout in the bottom of the ninth when Bryce Eldridge led off with a home run to right field, his fifth of the season. But Milner retired the next three batters, striking out Casey Schmitt and getting Rafael Devers to strike out looking to end the game.

The Cubs’ bullpen combined for three innings of one-run ball. Sam Hentges, Ryan Walker and JT Brubaker each threw scoreless relief for the Giants, with Brubaker working two innings and striking out one.

Seiya Suzuki led the Cubs’ offense with two doubles and an RBI. Busch finished 1-for-3 with the homer and three RBIs. Pete Crow-Armstrong doubled in the third inning for Chicago’s only other extra-base hit.

For the Giants, Eldridge was the lone bright spot, going 3-for-4 with his solo homer. The rest of the Giants lineup combined for one hit. Assad faced only 21 batters over six innings, throwing 63 pitches.

The game, which drew 38,115 fans, lasted 2 hours, 31 minutes.

Chicago’s victory came after a split of a four-game series in Colorado earlier in the week. The Cubs lost the first two games at Coors Field before winning the finale 9-3 on Thursday. San Francisco, meanwhile, had dropped two of three games at home to Washington before this series opener.

The teams have now played four times this season. The Giants won a pair of extra-inning games at Wrigley Field earlier this month, including a 2-1 victory in 10 innings on June 7, while the Cubs took the middle game of that series 3-2 in 10 innings on June 6. San Francisco also routed Chicago 18-3 on June 5 in the most lopsided meeting of the season.

The Cubs will send a starter to the mound Saturday in the second game of the series. San Francisco will counter with a pitcher as both teams look to build momentum. Chicago returns home after the series to face Colorado, Toronto and the New York Mets over the next week.

Interstat’s game simulator had projected a final score of San Francisco Giants 5, Chicago Cubs 3. Interstatl’s ELO system had projected the Cubs with a 53.40 percent probability to win. San Francisco had been installed as a pregame favorite with a spread of -1.5. The total score of 6 went over the over/under line of 8.