The race in the National League West tightened last night as the Dodgers won their seventh straight game and the Braves lost their seventh straight. Los Angeles now trails Atlanta by only a half-game; on July 30, the Braves held a 10 1/2-game lead over the Dodgers.

In Los Angeles, Pedro Guerrero hit Jim Kern's first pitch of the 13th inning into the left-center field pavilion, giving the Dodgers a 3-2 victory over the Reds. The victory was Los Angeles' 11th in 12 games.

Kern (1-5) had come on in the 11th inning. He worked out of a bases-loaded, none-out jam, then left two on in the 12th before Guerrero's homer, his 22nd of the season.

Dodger reliever Dave Stewart (7-6) retired the last 18 batters to earn the victory. Stewart, who was 3-1 against the Reds last year with one save, walked one and struck out five in his six innngs of hitless relief.

The Dodgers' other runs came when Steve Sax led off the first with a single to center and stole second. Dusty Baker singled in Sax and advanced to second on Guerrero's single. Ron Cey walked to load the bases and Steve Garvey's sacrifice fly to center field scored Baker.

In San Francisco, Jim Barr pitched a three-hitter for his first victory as a starter in two years as San Francisco beat visiting Atlanta, 5-0.

Atlanta Manager Joe Torre held a 10-minute meeting with his players afterward. He wouldn't discuss the subject but said "it's obvious we've lost our spirit. We don't have any life."

Barr, who started one game in April and has 36 relief appearances, walked none and struck out two. Barr (2-2) allowed singles in the fourth, fifth and sixth.