Tyler Fitzgerald drove in three runs and finished a single shy of the cycle as the San Francisco Giants posted a 10-4 road victory over the Philadelphia Phillies on Monday in the opener of a four-game series.

Mike Yastrzemski also finished with three RBIs for San Francisco, which has won four of its last five games. Willy Adames chipped in two hits and a home run in support of Landen Roupp (1-1), who gave up four runs and six hits over five innings with eight strikeouts.

Taijuan Walker (1-1), after allowing no runs in either of his first two starts, was charged with six runs (four earned) and six hits in five innings. Nick Castellanos contributed a home run and an RBI single for the Phillies, who have dropped four of their last five.

Philadelphia opened the scoring with three runs in the bottom of the first against Roupp. Bryston Stott led off with a single Trea Turner drove him in with a double to left. The Phillies added two more runs in the inning, including Castellanos’ RBI single.

The lead didn’t last long, however, as San Francisco answered with six runs in the top of the second. Wilmer Flores delivered an RBI single early in the frame before Patrick Bailey hit a grounder to Walker — a potential inning-ending double-play ball — that the veteran right-hander threw into center field.

Two pitches later, Fitzgerald launched a three-run home run over the left-field wall, making it 5-3. Adames put an exclamation point on the inning with his first home run as a Giant — a shot over the wall in right-center.

The Phillies threatened in the fourth, putting runners on second and third with nobody out. However, Roupp recovered to retire the next three hitters to escape the jam.

Castellanos lifted a solo home run in the fifth but Yastrzemski countered with a two-run homer in the seventh as the visitors went ahead 8-4. Fitzgerald tripled and scored ahead of Yastrzemski’s blast.

The two combined for another insurance run in the ninth, as Fitzgerald led off with a double and scored on Yastrzemski’s double. Matt Chapman’s RBI single capped the scoring.