Rodriguez was out of the starting lineup for the second straight day Saturday for the middle game of the Subway Series against the Mets at Citi Field.
Having lost his third base job while serving a season-long drug suspension last year, A-Rod was shifted to designated hitter this season. He played twice at first during spring training, started there on April 11 against Boston, then moved to first for the final two outs versus Texas on May 23.
Rodriguez took grounders at first ahead of the Yankees' late-season series at Atlanta.
"It just didn't look right, so we decided not to do it," Yankees manager Joe Girardi said. "He doesn't look comfortable. As much as we thought that maybe it might work, it just didn't work."
Rodriguez has been the Yankees' best offensive player, hitting .255 with 32 homers and 83 RBIs. He is on track to play a full season for the first time since 2007.
He pinch hit and walked in Friday's 5-1 loss to the Mets, then pinch hit again and flied out in Saturday's 5-0 win. Girardi said if A-Rod had played the field more often during the season, his production at the plate might have decreased.
"We needed his offense," Girardi said. "Let's not forget that he's 40 years old, and trying to run him out there for defense, there's probably not going to be a ton of range, and it's something that he's not comfortable doing."