DENVER -- Aaron Cook stayed with what was working and earned his second straight win.
Cook threw almost all sinkers in 81 pitches over seven strong innings and Dustan Mohr homered and drove in two runs, leading the Colorado Rockies to a 4-2 victory Saturday night over the Chicago Cubs.
The last-place Rockies won for the third time in nine games, snapping Chicago's three-game winning streak.
"I knew I had a good sinking fastball from the first inning," Cook said. "From that point on I used very few breaking balls and changeups and stayed with my sinking fastball."
Cook (2-1) allowed one run and seven hits for his second consecutive win. He has yielded seven earned runs in 31 1/3 innings over his last four starts.
Cook had two surgeries to relieve blood clots in his lungs, nearly costing him the entire 2005 season.
"Here's a guy that has been through so much over the past year," Colorado manager Clint Hurdle said. "He's put all that behind him to become a very confident pitcher. Tonight his confidence in his sinker helped him get 13 groundball outs."
Mike DeJean gave up a run in the eighth before Brian Fuentes worked the ninth for his 21st save in 24 opportunities. He retired Derrek Lee on a grounder with a runner on to end it.
"That at-bat is what a closer lives to see," Fuentes said of Lee's nine-pitch at-bat. "I threw him three changeups and nearly everything I had before I got him."
Mohr connected off Kerry Wood in the eighth for his 14th homer, extending the lead to 4-2. Todd Helton hit an RBI single for the Rockies, and left fielder Matt Holliday made a run-saving catch.
Lee had two doubles. Pinch-hitter Todd Hollandsworth and Aramis Ramirez each drove in a run for the Cubs.
Glendon Rusch (5-6) allowed three runs and seven hits in six innings. He is 0-3 in his last six starts and hasn't won since June 2.
"I pitched as well as I could in this ballpark," Rusch said. "Cook pitched better."
With the Cubs trailing 3-1 in the eighth, Lee doubled with one out against DeJean and scored on Ramirez's single.
DeJean loaded the bases but retired Neifi Perez and Corey Patterson to end the threat.
"We left the bases loaded in the eighth inning, but that didn't cost us the game," Chicago manager Dusty Baker said. "Defense did. We gave them two runs."
Colorado scored twice in the first inning. Helton, who struck out three times the day before, had an RBI single and scored from third when second baseman Todd Walker booted Todd Greene's grounder with the bases loaded.
Holliday singled and scored on Mohr's single in the third, making it 3-0.
Cook worked out of minor jams in each of the first four innings. Michael Barrett doubled to start the second, but Cook retired the next three batters without letting the ball leave the infield.
The Cubs got on the board in the seventh with a double by Perez and Hollandsworth's RBI single with two outs to make it 3-1.
"Those were big innings for me," Cook said. "I got two groundball outs in each of those innings."
The start was delayed 20 minutes by rain. ... Cubs SS Nomar Garciaparra was given one more day off to rest his sore lower back, but appeared as a pinch hitter. ... The crowd of predominantly Cubs fans booed Cook when he walked to the mound in the first inning. ... Helton returned to the No. 3 spot in the batting order after one game hitting cleanup. ... Colorado OF Larry Bigbie left in the third inning with soreness in his right Achilles'.