Chicago loaded the bases in the seventh and scored on an infield single by Aaron Cunningham and a wild pitch by Kraig Sitton.
Charlie Blackmon tripled to open the game and scored one out later on Carlos Gonzalez's groundout. It was a tough inning for Cubs starter Jeff Samardzija, who took a liner by Michael Cuddyer off his leg.
"I'm pretty used to these comebacker, get drilled kind of things," Samardzija said. "It happened a few times last year. It's part of pitching. Protect the vital organs and hopefully [the ball] stops close to you and you can get the guy out."
Ryan Kalish reached on a throwing error by shortstop Troy Tulowitzki to lead off the Chicago first, stole second, reached third on a wild pitch by Tyler Chatwood and scored on a throwing error by catcher Mike McKenry to tie the game.
Chatwood developed into a dependable Major League pitcher last season, going 8-5 wth a 3.15 ERA in 20 Major League starts, 111 1/3 innings pitched. But he had surgery to remove a bothersome bone chip from his right elbow in October. He has worked this spring with no problems. Wednesday was his first Cactus League appearance this year.
"Once you get out there and get back in a game and get the adrenaline going, you just let your competitiveness take over," said Chatwood, who allowed one hit and an unearned run over 2 2/3 frames. "That helped me out a lot that outing."
The Rockies loaded the bases with one out in the third, and Samardzija walked Gonzalez to force in a run. Tulowitzki followed with a sacrifice fly to go ahead, 3-1. Samardzija exited after giving up three runs on four hits over three innings.
The Cubs cringed in the third when Baez, their top prospect, fouled a ball off his left ankle, and fell to the ground. He lay there a few seconds, and after getting checked by an athletic trainer and manager Rick Renteria, stayed in the game.
Baez looked just fine in the sixth when he hit an opposite-field home run, his second this spring. Kottaras followed with his first blast to tie the game at 3.
Up next: The Rockies will meet the Brewers in Phoenix, with righty Jordan Lyles making his second start of the spring at 1:05 p.m. MT on Thursday in a game that will air on MLB.TV. Acquired from the Astros during the offseason, Lyles will be making his second Cactus League start. He went two innings and gave up two runs (one earned) against the Reds in his debut. Lyles is working on delivery issues that he hopes will give him consistency.