WASHINGTON -- Nationals manager Frank Robinson is seeing a fast change in the way Washington scores runs.

"Speed has been a difference on this ballclub," he said after Sunday's 6-1 win over the Milwaukee Brewers. "You can't always outslug a team."

Recently promoted Bernie Castro legged out an infield single in the seventh by beating pitcher Doug Davis to the bag, then scored the tiebreaking run from second base on a bloop single by Austin Kearns.

The next inning, Castro scored from first base on a three-run single by Felipe Lopez. Recently acquired outfielder Nook Logan, who had reached on a bunt single, also scored on that play.

Kearns also homered as the Nationals overcame a strong performance by Davis (10-11).

Four Nationals relievers combined for five hitless innings, with Saul Rivera (3-0) pitching the seventh to earn the win.

Nationals starter Mike O'Connor, who had a 75-pitch limit, allowed one run and three hits before being pulled after four innings and 69 pitches. Chris Schroder relieved O'Connor and struck out all six batters he faced before being lifted for a pinch-hitter in the sixth.

Davis was perfect for the first 4 1/3 innings before Kearns hit his 23rd home run.

"He was tough, hitting his spots," Kearns said. "He was just carving us up. I was just happy to get something."

In the seventh, Castro singled, moved to second on a sacrifice by Lopez and scored when Kearns looped a single to shallow right field.

Those three hits were the only one that Davis allowed. He struck out seven and walked none in seven innings.

The Brewers matched a season low with three hits.

"Doug was doing everything he could do to keep the score down and give us a chance to win the ballgame," manager Ned Yost said. "We couldn't get anything going."

After Kearns' single gave the Nationals the lead in the seventh, Washington added four runs in the eighth.

Brandon Harper led off with a single, Logan bunted for a single and Alfonso Soriano was hit by a pitch to load the bases with one out against Derek Turnbow.

Harper scored when Castro hit a grounder to Bill Hall, whose throw home sailed high.

Lopez followed with a single to right, scoring Logan, Soriano and the speedy Castro, who ran right through a stop sign from third-base coach Tony Beasley. Castro easily slid home because of a slow relay from right fielder Corey Hart to first baseman Prince Fielder.

"I knew he had a big lead," Lopez said of Castro. "He just went right when the ball was hit."

O'Connor hit Fielder with the first pitch of the second inning, then allowed singles to Kevin Mench and David Bell. Fielder scored the game's first run when Damian Miller hit a sacrifice fly.

After the second inning, only three more Brewers runners reached base, and all three were wiped out by double plays.

Notes

• 2B Jose Vidro started at first base for Washington, his first appearance there since May 29, 1999. The move allowed Washington to have a lineup of all righties and switch-hitters against the left-handed starter.
• CF Brady Clark singled on the second pitch of the game to break an 0-for-14 slump.
• O'Connor is winless in nine starts since June 8.
• The NL record for consecutive strikeouts by a reliever is seven, set by LHP Randy Johnson for Arizona in 2001.