Newly acquired Kevin Mitchell hit a pair of two-run homers and pinch hitter Chris Speier had a tie-breaking double in the eighth inning yesterday, sparking the San Francisco Giants to a 7-5 victory over the host Chicago Cubs.

Mitchell, who was acquired Saturday night in a trade with San Diego, started at third base and homered in the second and sixth innings. Chili Davis had three hits and scored on both of Mitchell's homers.

Joe Price, making his first 1987 appearance after being called up from Class AAA Phoenix, walked three and struck out four in two innings of relief to pick up the win. Price last won a game May 30, 1986, when he was with Cincinnati.

The Giants scored three times in the eighth to erase a 5-4 deficit. After Eddie Milner and Mark Wasinger got one-out singles off Ed Lynch (1-6), Robby Thompson bunted between Lynch and first baseman Leon Durham for a single that scored Milner.

Speier, pinch-hitting for Price, doubled down the left field line, driving in Wasinger and Thompson for the 7-5 lead.

Chicago starter Les Lancaster was called for three balks.

Mitchell hit his second home run off Lancaster in the sixth inning.

Cubs Manager Gene Michael was ejected in the third inning for arguing with home plate umpire Terry Tate about Mike Krukow allegedly scuffing the baseball. Cubs pitching coach Herm Starrette was thrown out in the sixth inning after an argument with second base umpire Jerry Crawford.

In the Saturday trade, the Giants got Mitchell, left-handed starter Dave Dravecky and left-handed reliever Craig Lefferts from the Padres for former all-star third baseman Chris Brown and left-handers Mark Davis and Keith Comstock and right-hander Mark Grant.

Cardinals 4, Braves 1:

Ozzie Smith has always been known for his glove. Yesterday in Atlanta, his bat got all the attention.

Smith had four hits, including a bases-loaded single in the seventh inning that drove in two runs and ended a tie in pacing the Cardinals to a sweep of the three-game series.

It was Atlanta's 10th loss in 13 games. The Cardinals improved the major leagues' best road record to 28-13.

Atlanta's Gary Roenicke had tied the score, 1-1, in the sixth when he hit his second home run of the year, a shot into the left field seats off left-hander Greg Mathews (6-6). It broke a 15-inning scoreless string by the Braves.

Reds 7, Mets 5:

In Cincinnati, Dwight Gooden, in his briefest appearance in two years, was rocked for nine hits and six runs in three innings. Tom Browning, just recalled after a month in the minors, scattered six hits over seven innings for the Reds.

Cincinnati won three of four games in the series, including the final three.

Gooden (5-2) struck out two of the first three batters he faced but gave up six hits and five runs in the second inning before being lifted after three innings. It was his shortest stint since he lasted 2 1/3 innings July 4, 1985, against Atlanta.

Astros 8, Phillies 2:

In Philadelphia, Billy Hatcher had four singles, drove in one run and scored twice, helping make a winner of Mike Scott.

Scott (10-4) gave up six hits and struck out six but walked a career-high seven in six innings. Larry Andersen pitched three innings for his second save.

Philadelphia starter Kevin Gross (8-6) allowed four runs but only two were earned.

Dodgers 6, Pirates 1:

In Pittsburgh, Orel Hershiser shut out the Pirates on one hit over five innings before leaving with an injury, and Dan Heep drove in two runs with a pair of doubles, his first hits in a Los Angeles uniform.

Hershiser (10-7) left the game because of stiffness in his lower back.

Hershiser, whose earned run average is 0.75 over his last six starts, faced the minimum 15 batters, allowing only Andy Van Slyke's one-out single in the fourth inning. He threw only 46 pitches.

Padres 3, Expos 2:

John Kruk homered with two out in the top of the ninth inning to break a 2-2 tie. Kruk hit a 3-0 pitch from reliever Jeff Parrett (1-3) for his eighth homer.

Rich Gossage (1-1) pitched two innings to get the victory. Gossage was the losing pitcher Saturday night when Hubie Brooks hit a homer in the bottom of the ninth to beat San Diego, 4-3.