San Francisco ? Vladimir Guerrero broke out of a slump by going 3-for-4 with a tiebreaking, two-run homer as the Montreal Expos defeated the San Francisco Giants, 6-4, Tuesday night in a game that featured a odd infield-fly play.

Guerrero, hitless in his previous 13 at-bats, singled in the first, doubled in the third and homered in the seventh as the Expos (24-15) moved nine games over .500 for the first time since July 17, 1997, when they were 51-42.

The Giants, the National League’s top team after the first month, have lost four straight for the first time since Aug. 14-18. San Francisco has lost five of its last seven to the Expos in Pacific Bell Park.

Marquis Grissom went 4-for-4 for San Francisco.

A strange play highlighted the Giants’ four-run fifth inning as they tied the game.

With Montreal ahead 4-3, the bases loaded and one out, Giants slugger Barry Bonds popped up the ball between the mound and home plate.

Plate umpire Jim Joyce signaled an infield fly, meaning Bonds was out and runners could advance at their own risk after the ball either was caught or dropped and touched.

The ball fell on the infield grass in front of home plate, between catcher Michael Barrett, pitcher Dan Smith and third baseman Fernando Tatis.

Neifi Perez tagged up at third and ran home after Tatis picked up the ball and touched home plate, apparently thinking it was a force play, then handed the ball to Barrett. The teammates were chatting, with their backs to the plate, as Perez came across.

The play was ruled a fielder’s choice, without an RBI.

The three Expos began arguing with Joyce, prompting Montreal manager Frank Robinson — who formerly worked as disciplinarian in the commissioner’s office — to scold them and set them straight. They then dispersed.

San Francisco's Neifi Perez pumps his fist after scoring on a fielder's choice as Montreal infielders and catcher Michael Barrett argue with home-plate umpire Jim Joyce in the fifth inning. Barry Bonds had hit the ball and was called out on the infield-fly rule, which allows runners to advance at their own risk. The ball fell in front of the plate between catcher Michael Barrett, pitcher Dan Smith and third baseman Fernando Tatis. Despite Perez' run, the Giants fell to the Expos, 6-4, Tuesday in San Francisco.

Smith (2-1) pitched 22¼3 innings, striking out two. Rocky Biddle got three outs in the ninth for his 10th save in 11 chances.

Reds 7, Cardinals 2

St. Louis — Cincinnati beat St. Louis behind two-run homers from Austin Kearns and Adam Dunn. Cincinnati shortstop Barry Larkin reinjured his left calf, strained it while running the bases in the second inning.

Rockies 9, Mets 8

Denver — Preston Wilson had three RBIs, including a two-run homer, and Colorado rallied from a 7-0 deficit. Tom Glavine pitched six shutout innings before tiring in the seventh, and Mike Piazza hit two homers for the Mets.

D’backs 6, Phillies 1

Philadelphia — Quinton McCracken hit a two-out RBI single off Jose Mesa that drove in the go-ahead run in a five-run ninth inning off Jose Mesa (1-3).

Astros 6, Pirates 3

Pittsburgh — Richard Hidalgo hit a tiebreaking three-run, ninth-inning double off Mike Williams (0-2) that was just out of the reach of right fielder Rob Mackowiak. Houston rallied from a 3-1 deficit to beat Pittsburgh for the 10th straight time.

Cubs 7, Brewers 2

Milwaukee — Shawn Estes (4-3) won his third straight decision, getting a victory on the road for the first time this season. Pitching against Milwaukee for the second time in six days, he allowed two runs and five hits in seven innings.

Padres 6, Marlins 5 (10)

San Diego — Ramon Vazquez singled in the winning run in the 10th inning, sending the Marlins to their first loss under new manager Jack McKeon.

Braves 3, Dodgers 1

Los Angeles — Gary Sheffield hit a tiebreaking homer in the eighth off Paul Quantrill (0-2). The Braves are 23-4 after losing eight of their first 12. It’s their best 27-game stretch since 1954.