DENVER — The Rockies' starters have found their groove just as the offense has gone cold.
It has added up to a rough month for the surprising contenders in the NL West.
Jeff Samardzija pitched effectively into the eighth inning and Anthony Rizzo doubled home the go-ahead run in the seventh, leading the Chicago Cubs to a 3-1 victory over Colorado on Friday night.
Samardzija baffled the struggling Rockies hitters, using a devastating split-finger fastball to stymie an offense that hasn't made much noise over the past month.
"Tonight the guy was nasty and dominated," outfielder Michael Cuddyer said. "You've got to tip your hat every once in a while. He pitched really well."
The Rockies have been pitching well, too, but the offense hasn't capitalized on several strong outings. Jorge De La Rosa gave Colorado another one Friday night, allowing one run on five hits over six innings, but was left with a no-decision after the lineup managed just one run on five hits against the last-place Cubs.
It has been a trend for the Rockies, who have been held to fewer than three runs 11 times since June 23. Colorado has gone 7-13 in that stretch to fall five games below .500.
Getting All-Star shortstop Troy Tulowitzki and Dexter Fowler back before the break hasn't sparked the offense.
"I'm not overly concerned about our offense," manager Walt Weiss said. "Getting back to full strength here, I think our offense will be rolling."
Being healthy didn't help against Samardzija (6-9), who kept the Rockies in check by limiting them to one run on four hits in 7 1-3 innings, bouncing back after tying a career high by allowing nine runs in a 13-2 loss to the Los Angeles Angels on July 10.
He walked three and struck out six, including striking out the side in the seventh, when he set down All-Stars Carlos Gonzalez, Tulowitzki and Cuddyer.
"He doesn't get a lot of credit, but I think he's one of the better pitchers I've seen," Nolan Arenado said. "Every time he threw that splitter it was landing right on the plate. He was getting us pretty good with that."
Alfonso Soriano added a home run, his 17th, and Junior Lake, recalled by Chicago from Triple-A Iowa before the game, had three hits in his major league debut, including a double in his first career at-bat. Darwin Barney drove in an insurance run with a ninth-inning double.
D.J. LeMahieu doubled off Kevin Gregg to start the ninth and advanced to third on a ground out by Gonzalez. Tulowitzki walked before Gregg induced Cuddyer to ground into a game-ending double play for his 18th save in 20 chances.
Chicago regained the lead in the seventh, sparked by Cody Ransom's two-out walk off reliever Edgmer Escalona (1-3). Rizzo followed by lining a double down the right field line. He was thrown out trying for third but not before Ransom had crossed the plate with the go-ahead run.
Soriano gave the Cubs a 1-0 lead when he homered to start the fourth inning, driving De La Rosa's 0-1 pitch into the stand of evergreens beyond the center field wall. It was his 389th homer, tying him with Hall of Famer Johnny Bench for 57th on the career list.
"That was a mistake. I tried to throw away and it ran to the middle," De La Rosa said. "As soon as you throw the ball like that you know."
Fowler evened the score when he led off the Rockies' half of the fourth with a homer, his 11th. He drove Samardzija's first offering beyond the center field wall in almost the same spot as Soriano's.
The Rockies had a chance to go in front after Tulowitzki and Cuddyer hit consecutive two-out singles. With Todd Helton up, a low pitch skipped past Welington Castillo, but the ball bounced off the backstop and the catcher corralled it, making an off-balance throw to Samardzija covering at home just in time to tag out Tulowitzki, who had broken for the plate.
"That backstop is real short and it bounced right back to the catcher," Weiss said. "He made a nice play and Samardzija made a nice play on the tag. It's tough to know where the ball's going to bounce."
NOTES: Fowler's home run was his first since hitting two against the Los Angeles Dodgers on June 2. ... Tulowitzki had two hits for his 24th multi-hit game of the year. ... The Rockies opened the second half with a 10-game homestand, while Cubs began a 10-game road trip. ... Rockies right-hander Juan Nicasio (5-4) is set to pitch Saturday night's game against the Cubs. He'll be opposed by RHP Carlos Villanueva (2-5).