PITTSBURGH — It wasn't Aaron Cook's best performance, but the Colorado Rockies pitcher still added to his surprising win total.

Cook tied Arizona's Brandon Webb for the National League lead in victories, Troy Tulowitzki kept up his torrid pace with three more hits and the Rockies avoided a sweep with a 7-4 victory over the Pittsburgh Pirates Wednesday night.

Cook (14-6) pitched seven innings, allowing four runs and nine hits to win his third straight start. The right-hander, in his seventh season, had never won more than nine games before this year.

He pitched out of trouble in the second, third and fourth innings, stranding two runners each time. He allowed all of his runs in the fifth before retiring seven of the final eight batters he faced.

"The term is effectively ugly," Cook said of his outing. "The team gave me some runs early, and that made things easier."

Colorado manager Clint Hurdle had another term: gutsy.

"There was some grit," he said. "He did not have his best stuff."

Cook needed 108 pitches to get through his outing, his fifth-highest total in 23 starts.

"He was behind in the counts a little bit," Colorado catcher Chris Iannetta said. "He battled through it."

Iannetta hit a three-run homer and Garrett Atkins, Matt Holliday and Willy Taveras had two hits each for Colorado, which improved to 10-3 since the All-Star break.

Tulowitzki went 3-for-4 with a double and an RBI. Since coming off the 15-day disabled list on July 21, the shortstop has raised his average from .166 to .241 by going 20-for-36 (.556).

The Pirates, who rallied for wins in the first two games of the series, cut into a 6-0 deficit but couldn't complete the comeback this time.

Iannetta's home run capped a four-run fifth against Pittsburgh starter Zach Duke and gave Colorado a 6-0 lead. Atkins had an RBI single in the inning.

Duke said he left a fastball up to Iannetta.

"That's the difference in the game right there," he said. "It did the most damage. If I get the ball down, I get the result I want, a ground ball. It's frustrating."

Duke (4-9) went five innings, allowing six runs and eight hits. The left-hander dropped to 0-5 in his past nine starts, and hasn't won since June 9, against Arizona. In three second-half starts, Duke has an 11.25 ERA.