Eight was the magic number for both the Dodgers and the Braves. Last night, Los Angeles moved into first place in the National League West for the first time in the season when its winning streak reached eight and Atlanta's loss streak reached eight.

At Dodger Stadium, Rick Monday and Steve Garvey homered and Fernando Valenzuela (15-8) pitched a six-hitter, beating the Cincinnati Reds, 11-3. That, combined with the Braves' 3-2 loss to the Giants at Candlestick Park, gave the Dodgers a half-game lead over Atlanta, which they trailed by 10 1/2 games July 30.

"As defending world champions, we have something to prove," said Steve Garvey. "We can't forget San Diego, we can't forget San Francisco, and we certainly can't forget Atlanta. But I like our team."

The loser was Tom Seaver (5-12), who has been defeated in seven of his last eight decisions.

In San Francisco, Milt May homered off Al Hrabosky in the seventh inning to beat Atlanta; it was the Giants' ninth straight victory.

May, the second batter to face Hrabosky (2-1) hit a 1-0 pitch down the right field line; the ball was fair by about a foot. The Giants moved within five games of first place in the NL West with their 31st come-from-behind victory of the season.

Winner Bill Laskey (11-8) shut out Atlanta over the final eight innings after Dale Murphy hit his 29th homer of the season with Larry Whisenton on base in the first. The Braves had gone 20 innings without scoring before Murphy homered.