Rockies assistant athletic trainer Scott Gehret attended to Gonzalez briefly, then Gonzalez disappeared into the Rockies' dugout. Tyler Colvin replaced Gonzalez and delivered an RBI single to put the Rockies up 1-0. X-rays were performed immediately, revealing the contusion. Gonzalez is listed as day to day.
Center fielder Dexter Fowler, whose day ended when hit on the right hand by a pitch in the third, said players hit in on-deck circles rarely happens, but he was involved in a similar incdent last year.
"I hit 'Tulo' [shortstop Troy Tulowitzki], but he was in the dugout, in the hole," Fowler said. "Sometimes, you try to avoid these things, but sometimes you can't. It's part of the game."
Gonzalez entered the game batting .299 with 18 home runs, which ranks second in the National League behind the 19 of the Phillies' Domonic Brown, and 52 RBIs, which are third in the league. Gonzalez also entered the game leading the league with 38 extra-base hits and second in slugging at .618, behind teammate Troy Tulowitzki's .639.
The Gonzalez and Fowler incidents occurred a day after the Rockies designated Eric Young Jr. for assignment and decided to go with four outfielders and 13 pitchers.
Gonzalez already has been playing through pain. He has been dealing with a twisted left knee. To preserve it, he'll slow to a jog at times when it's unlikely he'll beat out a play at first base or reach a ball in the outfield.
"On deck here is fairly close, so it was due to happen," rookie third baseman Nolan Arenado said. "But it didn't look like it squared him up."
Fowler is day to day. Gonzalez and Fowler were the first of two scary injuries on the day for the Rockies, who also lost shortstop Troy Tulowitzki in the eighth after hurting his ribs diving for a ground ball. Tulowitzki broke a rib on his right side, an MRI later revealed, and he is expected to miss four to six weeks.
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, and follow him on Twitter @harding_at_mlb. This story was not subject to the approval of Major League Baseball or its clubs.