X-rays revealed he had a fracture in his left hand. Mark Reynolds pinch-ran for Nix and remained in the game at third base.
"I feel terrible," manager Joe Girardi said. "Obviously he's got a broken hand and he's going to be out for a while. I'm not sure what exactly we're going to do, but I feel really bad."
Nix, who is likely to miss the remainder of the regular season, played the hero for the Yankees in their 3-2 win in Game 2 of Tuesday's doubleheader, hitting a game-tying solo home run in the seventh inning and a walk-off single in the ninth.
For the season, Nix is batting .236 with three home runs, 24 RBIs and 13 stolen bases. He has also played solid defense for the Yankees, splitting time primarily between shortstop and third base while Alex Rodriguez, Derek Jeter and Eduardo Nunez were on the disabled list.
"I always talk about Nixy, he's a guy who does things right," Girardi said. "Maybe it's not always going to show up in the box score, all the things that he contributes, but he's a guy that just makes good decisions and does things right."
Josh Vitale is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.