PHOENIX (AP) _ Vladimir Guerrero hit a pair of two-run homers and the Montreal Expos cruised to a 9-3 victory over the Arizona Diamondbacks on Tuesday night.

The outcome allowed San Francisco, which beat Milwaukee 1-0, to widen its lead over the Diamondbacks in the NL West to a season-high two games.

Lee Stevens also homered off Arizona starter Brian Anderson, who lasted just 4 1-3 innings in his shortest outing since June 17. Anderson (9-5), allowed seven hits and six runs, walking three while striking out four.

Guerrero hit a two-run shot in the third inning and another _ his 28th _ in the fifth, giving him 90 RBIs. He also tripled in a spectacular, 3-for-5 performance.

Kelly Stinnett, Greg Colbrunn and Danny Bautista had RBI singles for Arizona.

Montreal starter Scott Downs, who sprained his left elbow in the course of throwing 65 pitches, gave up three runs and five hits in three-plus innings in his first appearance for the Expos since they acquired him from the Chicago Cubs on July 31.

The team said the elbow was X-rayed and would be re-evaluated on Friday in Montreal.

Felipe Lira (3-1) came in with the bases loaded in the fourth and gave up Bautista's tying RBI single. Then he got Anderson to hit back to the mound for a throw to home plate, forcing Colbrunn, and Tony Womack to hit into an inning-ending double play.

He pitched three scoreless innings before handing over an 8-3 lead to Steve Kline in the seventh.

The Diamondbacks took a 1-0 lead on Stinnett's RBI single in the second inning.

But Jose Vidro singled with one out in the third, and, after Geoff Blum flied out, Guerrero pulled a pitch into the Diamondbacks bullpen. Two pitches later, Stevens hit an opposite-field homer into the left field grandstand for a 3-1 lead.

After Arizona tied it in the fourth, Blum hit an RBI single before Guerrero crushed another pitch by Anderson 422 feet onto a picnic pavilion above the wall in right center.

Stevens hit a sacrifice fly after Guerrero's leadoff triple off Russ Springer in the seventh, and pinch-hitter Andy Tracy made it 8-3 with a run-scoring single.

Notes: It was Guerrero's fourth multihomer game this season and eighth of his career. ... Arizona C Damian Miller was scratched just before game time because of a left ankle sprain. ... Downs had his fifth no-decision in his last eight starts. ... Anderson dropped to 1-3 in his last eight starts.