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Lefty Barry Zito aims to snap a three-month winless drought on Monday night when the San Francisco Giants head to Coors Field to open a three-game series with the Colorado Rockies.

The 35-year-old southpaw was 4-3 on the season after a 5-2 defeat of his former team, Oakland, on May 30, but he's dropped six decisions in 15 appearances since.

He was shelled for six runs on seven hits while retiring just 11 batters in his most recent outing on Aug. 21 against Boston, when the Giants lost a 12-1 decision.

Zito hasn't pitched more than six innings since a no-decision against Miami on June 22 and hasn't struck out as many as five batters since a July 9 game against the New York Mets.

He's 8-4 in 22 career meetings with Colorado, with a 2.98 earned run average in 148 full innings.

Colorado replies with righty Juan Nicasio, who's gone three starts since his last loss.

The soon-to-be 27-year-old - his birthday is Aug. 31 - was 6-6 on the season after a 5-1 loss at Pittsburgh on Aug. 4, but he's since defeated the Pirates and gotten two no-decisions in three starts.

Nicasio has logged 17 1/3 innings in the subsequent three outings - in which the Rockies are 2-1 - and allowed 17 hits and seven runs.

He is 1-1 in four career starts against the Giants.

On Sunday in San Francisco, Ryan Vogelsong pitched eight shutout innings to help the Giants take a 4-0 win over the Pirates to wrap up a four-game series.

Vogelsong (3-4) gave up just two hits and a walk with five strikeouts, while Sandy Rosario left a man on second in the ninth to complete the shutout for the Giants, who took the final two games of this set after dropping five of six.

Pablo Sandoval hit a two-run triple, while Buster Posey and Joaquin Arias each drove in a run in the win.

In Miami, Nolan Arenado's tie-breaking RBI double in the top of the sixth inning proved to be the difference, as the Rockies edged the Marlins, 4-3, in the rubber match of a three-game set at Marlins Park.

Ryan Wheeler collected two hits, an RBI and a run scored, while Michael Cuddyer scored a pair of runs for the Rockies, who wrapped up a 10-game road trip at 4-6.

Jorge De La Rosa (14-6) allowed three runs on five hits and three walks over five frames to earn his fourth consecutive victory. Rex Brothers worked around a pair of walks in the ninth to secure his 13th save of the season.

The Giants won seven of the first 13 games with the Rockies in 2013, though Colorado took two of three when they let met, from June 28-30, at Coors Field.