Nix had taken batting practice Wednesday, but he began to feel stiff while standing in the field. He went to the batting cage for additional swings, felt worse and finally was scratched from that day's game against the White Sox.
It was another twist in an eventful spring for Nix.
Out of Minor League options and needing to prove the Rockies were correct in selecting him 44th overall in the 2001 First-Year Player Draft, Nix began the spring slowly offensively, but three of his six hits in Cactus League play are home runs and he has a .273 batting average and a .484 on-base percentage.
"I feel very blessed to have the opportunity to compete for this job, to go through the mental grind that it takes," said Nix, who has had back issues in the Minors but usually is better after one or two days off. "I'm thankful to be able to challenge myself."
The Rockies staged a six-man competition for the second-base job, with most candidates also playing other positions. The other pure second baseman, veteran non-roster invitee Marcus Giles, entered Friday hitting .304 with a .467 on-base percentage, three doubles and a triple.
Regarding other injuries, right-handed pitcher Jason Hirsh (right shoulder strain) played long toss on Thursday. He is scheduled to throw off a mound Friday, and he could throw a bullpen session on Sunday.
Right fielder Brad Hawpe (sore left elbow) went 3-for-6 with a three-run homer and a double against D-backs Minor Leaguers on Friday. Although he has healed enough to return to playing the field, the Rockies aren't pushing him.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.