DENVER -- A couple of bullpen sessions over the All-Star break helped Jeff Samardzija resolve the mechanical problems in his pitching delivery that had been bothering him much of the season.
The refinements were evident Friday night when Samardzija pitched effectively into the eighth inning, and Anthony Rizzo doubled home the go-ahead run in the seventh in the Chicago Cubs' 3-1 win over the Colorado Rockies.
"We changed a couple things with my mechanics, kept me on line a little more," Samardzija said. "But if you had asked me all year how I felt about my mechanics, I would say they were off, to tell you the truth, until today. So, I'm really excited to stop making adjustments and really just working on pitch selection and pitch location. As a pitcher, sometimes those things happen. It clicks for you, and you go from there."
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.
Samardzija (6-9) 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.
"Tonight, the guy was nasty and dominated," Michael Cuddyer said. "You've got to tip your hat every once in a while. He pitched really well."
Samardzija was able to paint the corners with his fastball and kept the Rockies off balance with a devastating splitter.
"It was so good tonight," Cubs manager Dale Sveum said. "It was diving out of the strike zone so much you couldn't even get swings at it sometimes."
"I was working both sides of the plate with my fastball, really established it for a strike, and when you do that, it makes your splitter that much better," he said. "Just being aggressive helped out a lot."
Added Cuddyer: "He throws 96 mph with an 83 mph splitter that was on tonight. He didn't walk many guys until the very end."
DJ LeMahieu doubled off Kevin Gregg to start the ninth and advanced to third on a groundout 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 Jorge 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.
Dexter 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.
De La Rosa went six innings and allowed one run on five hits.
Lake, an oufielder/infielder, filled the roster spot of outfielder Brian Bogusevic, who was placed on the 15-day disabled list with a left hamstring strain.
Sveum said he was extremely encouraged by Lake's exceptional debut.
"Since I've been here, that's the first kid that's come up and looked like a major leaguer, aggressive, aggressive on the bases," Sveum said. "He did a great job and swung the bat really nice."
The home run was Soriano's 15th extra-base hit since June 28, tops in the NL in that span. ... Fowler's home run was his first since hitting two against the Los Angeles Dodgers on June 2. ... The Rockies open the second half with a 10-game homestand, while the 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).