Right-hander Matt Garza takes the mound with an eye on a series sweep today when the Chicago Cubs collide with the visiting Arizona Diamondbacks in the finale of a three-game weekend series at Wrigley Field.

The Cubs were 8-1 winners in the series opener on Friday, then won a second straight game on Saturday when starter Ryan Dempster's scoreless innings streak extended to 33 innings amid trade rumors.

Dempster tossed six shutout innings and became the first Cub to hurl 33 straight scoreless innings since Ken Holtzman in 1969, helping Chicago to a 4-1 win over the Diamondbacks.

Dempster (5-3) fanned five, scattered four hits and walked three for Chicago, which has won four of its last five. The Canadian hasn't given up a run since May 30 and has won five straight starts.

"Like I said before, I am well aware of things going on, rumors and things like that," Dempster said. "But I'm a member of the Chicago Cubs and I'm trying to do my best job for this team."

He threw 89 pitches in his second outing since being sidelined with right lat tightness.

Luis Valbuena registered a pair of hits, an RBI and a run scored, while Reed Johnson and Geovany Soto each racked up two hits apiece.

Arizona's Joe Saunders (4-6) was charged with four runs - three earned - on eight hits for the D-backs, who have dropped eight of their past 11. Saunders had been on the disabled list since June 23 with tightness in his left shoulder.

Chicago's Garza, in his second season with the Cubs after arriving via trade from Tampa Bay, was 2-5 in his first 12 outings before a 12-3 interleague win over the Chicago White Sox on June 18.

He's alternated losses and wins since, dropping a 5-1 verdict to the Diamondbacks before beating Houston and losing at Atlanta.

Against Arizona on June 24, the 28-year-old allowed three runs on five hits in seven innings and fell to 1-1 in a pair of lifetime meetings with the D-backs.

He's 2-1 in six starts at Wrigley Field in 2012 with a 2.50 earned run average.

Arizona counters with righty Trevor Cahill, who meets the Cubs for the second time in his 114th major-league appearance.

The 24-year-old won five of his last seven starts before the All-Star break, including a 5-3 defeat of the Los Angeles Dodgers on July 7 in which he surrendered just three runs on six hits across seven innings.

Cahill was 2-5 in his first 10 starts of the year before a four-start win streak between June 3 and June 20 that included a complete game at San Diego and saw his ERA drop from 3.96 to 3.47.

The only previous meeting with the cubs was for the Oakland Athletics at Chicago on June 15, 2010, when he emerged with a 9-5 win after allowing four runs on six hits in 5 2/3 innings.

The Diamondbacks swept a three-game series in Phoenix in June, while the Cubs won last year's season series, 4-3. Arizona last won the season series in 2009, 4-2.