DENVER -- The Chicago Cubs were on the verge of a game-tying rally and possible rare road victory.
Unfortunately starter Chris Volstad had dug them a hole too big in the first three innings of Thursday's game with the Colorado Rockies.
"Home runs got me again," Volstad said. "It was a spinning curveball and a fastball in that got me. Other than that, it was singles mainly and four of them in the infield."
Volstad (3-11) allowed seven runs and 10 hits in three innings.
Jordan Pacheco and DJ LeMahieu homered, leading Colorado to a 7-5 victory and a three-game series sweep.
"Really there was no life," Chicago manager Dale Sveum said. "No breaking balls or sticking to the game plan."
Sveum couldn't understand why Volstad abandoned a game plan that was successful in an Aug. 26 start when he threw 6 2-3 scoreless innings.
"I don't know what was going on," Sveum said. "He pitched a pretty good game against these guys last time, just pitching down and away.
Pacheco, Wilin Rosario and Chris Nelson had two hits apiece for the Rockies, who had 12 hits in their final home game of 2012.
Rafael Betancourt relieved after a run was in and there with two on and no outs in the ninth. He gave up a run-scoring double to Alfonso Soriano before finishing for his 31st save.
Anthony Rizzo homered and had three hits and Luis Valbuena had two hits for the Cubs, who have lost five straight and nine of 10.
The Cubs (59-97) are on pace to surpass 100 losses for the first time since 1966.
Chicago trailed 7-3 in the ninth before rallying. Rizzo singled in the first run off Matt Belisle to bring on Betancourt. He allowed an RBI double to Soriano that made it 7-5 and put the tying run on second.
Betancourt struck out Starlin Castro and Josh Vitters and got Anthony Recker to ground out to end the game.
"We were one hit away from tying that game after a tough day, where balls were hit really hard and had nothing to show for it," Sveum said. "It was nice to be one ball from hitting the outfield grass to tying it up."
It was the eighth consecutive game the Rockies had 10 or more hits. They hit .305 at Coors Field this season to become the first team to hit more than .300 at home since the Yankees and Angels did it in 2007.
For the last six weeks Colorado's offense has been fueled by youth. Thursday's starting lineup featured six rookies and only one player -- Nelson -- who was in the opening day lineup.
Despite that, Colorado jumped on Volstad right away. Pacheco hit a three-run homer in the first, LeMahieu had a two-run shot in the second and Nelson had an RBI single in the third as the Rockies took a 7-3 lead.
It was enough for starter Jhoulys Chacin to get his first win since Sept. 1. Chacin (3-5) allowed three runs and seven hits, walked four and struck out two in five innings.
Brett Jackson's RBI single in the second was Chicago's first run in a span of 13 innings.
NOTES: Cubs 2B Darwin Barney extended his errorless streak to 141 games to tie for the major league record. Placido Polanco of the Detroit Tigers did it in 2007. ... The Cubs have lost 16 straight in NL West ballparks. ... Valbuena has 15 multiple hit games.