(Sports Network) - Left-hander Barry Zito seeks his first career win against Washington today when the San Francisco Giants travel to Nationals Park for the third of four games with the host Nationals.

Zito was 0-8 through his initial nine starts of the season before finally getting on the winning side with an 8-2 defeat of the Florida Marlins on May 23.

He's gone back to his winless ways since, however, getting a no-decision and a loss in two starts while being touched for 13 hits and eight earned runs in 10 1/3 innings.

He's 0-1 with a 3.50 earned run average in three lifetime starts against Washington.

On the mound for the Nationals will be right-hander Garrett Mock, who will be making his major- league debut.

The right-hander is replacing veteran Odalis Perez, who's being held out for a start due to tendinitis and the club's desire not to pitch John Lannan on short rest.

Mock was acquired from Arizona in August 2006 in exchange for Livan Hernandez and was 3-2 in 11 starts with a 3.06 ERA for Triple-A Columbus this spring.

He has struck out 51 batters in 62 1/3 innings.

On Saturday, John Bowker's one-out grand slam highlighted a six-run eighth inning for the Giants in their 6-0 defeat of the Nationals.

Pitchers Jonathan Sanchez and Shawn Hill matched zeroes for seven innings before Hill allowed a single and a double with one out in the eighth and was lifted in favor of Luis Ayala.

Bengie Molina followed with an RBI single and a subsequent Rich Aurilia single made it 2-0, before Bowker drove a pitch out of park to right field.

Sanchez allowed four hits and struck out four in seven innings to earn his fifth win.

Hill was charged with the loss, allowing seven hits and being charged with two of the eighth-inning runs.

Washington is 9-6 versus San Francisco since the start of the 2006 season, winning five of eight at home in that span.