Rox win 15th straight vs. NL Central

"I rushed to get dressed and get loose," Marshall said. "That's the first time I've done that. It was tough."

The Rockies took full advantage of the late scratch of Zambrano because of a lower back injury, jumping on Marshall for three runs in two innings en route to a 6-2 victory in the opener of a four-game series. Colorado has won 15 straight against NL Central teams.

"It was a big deal," said the Rockies' Todd Helton, who singled twice to drive in two runs and extend his hitting streak to 12 games. "We ate up their bullpen a little bit. It should help us the rest of the series."

About 15 minutes before the start of the game, Zambrano was scratched because of a recurrence of the lower back injury.

Zambrano, who was 7-4 with a 3.35 ERA entering the game, worked a season-low three innings in his last start against Florida on Aug. 1, before leaving the game with lower back stiffness. He had worked out with no complaints since then, and Cubs manager Lou Piniella had said before the game that there were no concerns about Zambrano's back.

"When he went out there to warm up, he says after he threw two or three pitches, his back tightened up and he started getting spasms," Piniella said. "This is something that happened right before the ball game. If he had been complaining about anything, obviously, we wouldn't have scheduled him to pitch."

Zambrano was sent back to the hotel and was reported to still be in discomfort. Piniella said Zambrano would be sent to Chicago today and undergo an MRI.

The Rockies got a solid start from Ubaldo Jimenez (9-9), who allowed two runs — one earned — and four hits in 6 2/3 innings for his third consecutive victory.

"My first thought was 'It's too bad for him,'" Jimenez said of not having to go against Zambrano. "I hope he wasn't hurt too badly."

Chris Iannetta hit a two-run homer in the fourth off Jeff Samardzija, helping the Rockies to their sixth win in eight games.