DENVER -- It's an age-old axiom in baseball: Don't walk the pitcher. But Carlos Villanueva broke that cardinal rule, giving Rockies counterpart Juan Nicasio a free pass to extend the fourth Saturday as his night unraveled and the Cubs fell to the Rockies, 9-3, at Coors Field.
After throwing away a chance to get the final out of the inning against the pitcher, the game still knotted at 1, Villanueva gave up two more runs that inning. He was yanked without recording an out in the fifth with seven earned runs to his name. The 3-2 slider to Nicasio marked the beginning of the end for the Cubs' starter.
"It was all set up just to get the pitcher out, and it was smooth sailing from then," Cubs manager Dale Sveum said. "And obviously the flood gates opened and everything just fell apart."
The Cubs' one-run lead after third baseman Luis Valbuena went deep turned into a two-run deficit when the Rockies scored three runs in the fourth. Todd Helton opened the rally with a single, moving to third on a Wilin Rosario double that cruised past the outstretched glove of Nate Schierholtz in right field, then scored on a groundout.
Swinging and missing on two breaking pitches, Dexter Fowler saw a pitch in the strike zone and launched it into the right-field corner for a triple to put the Cubs in a 3-1 hole.
"That kind of changed the game around a little, walking [Nicasio] on a 3-2 slider and throwing Fowler a 3-2 fastball. That's a little backward," Sveum said. "It turned the whole momentum around in the whole game."
Even after the fourth, Villanueva started the fifth with a chance to salvage a quality start. But the night took a decidedly sour turn for Villanueva, making just his third start since a stint in the bullpen, in the fifth.
Rockies left fielder Carlos Gonzalez sparked the fire when he crushed his 26th homer on a 2-1 slider into the second deck of Coors Field, high above the Rockies' bullpen.
"That was a good swing," Gonzalez said. "Soon as I hit the ball, I knew that was out of the ballpark. I didn't know where it was going to land, but it was going to go pretty far."
Colorado followed with four consecutive singles, the third off the bat of Helton, the final batter Villanueva faced. The Rockies have proven a prickly thorn in Villanueva's side. The only other time he gave up more than four earned runs this year was on May 14, when he also surrendered seven runs against Colorado.
This night ended in similar fashion for Villanueva, who allowed nine hits and walked four. The righty now has an 11.57 ERA in 13 appearances (two starts) against Colorado.
"I guess I'm glad we only play them twice this year," Villanueva said. "Because you know what, it was basically a photocopy of last time. I tried some things different today, it seemed to work somewhat the first couple innings, but it's a team that's given me trouble throughout my career for some reason."
It was the Cubs' fourth loss in their past 11 games, putting a streak of four straight series victories in jeopardy. Chicago will look to take this series and the season series with the Rockies in Sunday's rubber match.
The Cubs' clubhouse sits at the center of the non-waiver Trade Deadline rumor mill, with starter Matt Garza expected to be dealt soon and other roster shake-ups on the horizon. Fifteen games back in the National League Central, the roster could look much different come August 1.
"You try to as robotic as possible when it comes to that and not have that much emotion, because it's going to happen, it's happened before, it's happened to me a couple times," Villanueva said "It's a part of this roller coaster of a business that we do. You have to ride the good one and the bad one, so we feel pretty comfortable with each other in here."
The Cubs struck first when Valbuena launched a solo home run -- his ninth of the year -- into the fir trees on the backside of the Rockies' bullpen. But Nicasio quickly silenced them, limiting Chicago to just three hits over five innings.
More scoring had to wait until reliever Adam Ottavino entered in the sixth. Alfonso Soriano followed a leadoff single by Anthony Rizzo with a double into deep right-center, and a soft Schierholtz grounder to first was enough to score Rizzo from third and trim the Rockies' lead to 5.
Chicago's offense showed comeback potential when Darwin Barney knocked a leadoff single to right in the seventh off Ottavino. While Valbuena plated Barney, Starlin Castro hit into a double play that ended any hopes of a late offensive surge.
Reliever Michael Bowden and Hector Rendon combined for three scoreless innings, but Blake Parker allowed two more runs in the eighth off a Troy Tulowitzki double.
Ian McCue is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.