The compact Nix, who is listed at 5-foot-11, felt that number belonged on a lanky fellow. So he'll wear No. 4. Third-base coach Mike Gallego will switch to No. 7.
"It was between four and seven, and I just like four a little better," said Nix, who was the Rockies' top pick -- 44th overall -- in the 2001 First-Year Player Draft but will be making his Major League debut Monday afternoon against the Cardinals.
Nix's preferred number is eight, but that's occupied by veteran catcher Yorvit Torrealba.
The other jersey change was reserve outfielder Scott Podsednik going to No. 22 after wearing 29 in Spring Training.
This is the second straight year Gallego has had to switch numbers. Last year, he gave up No. 2 for shortstop Troy Tulowitzki, who emerged as a leader and came close to winning the National League Rookie of the Year Award.
The Rockies can only hope Nix's swap with Gallego works as well.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.