Called up from Triple-A Scranton/Wilkes-Barre on Thursday, Nunez has been a defensive replacement each of the past two days, fouling out in his lone at-bat.
Nunez was promoted to the big club for just this reason, providing extra infield depth behind Ramiro Pena, with Rodriguez's status uncertain for the next several days.
"He finds a way to put the bat on the ball," manager Joe Girardi said of Nunez. "We believe that he can be an exciting player. They started playing him at second base and third base in Triple-A so that we would have some options. We believe this kid is gifted athletically and could be a real plus for us."
Nunez had spent the entire season at Triple-A Scranton/Wilkes-Barre, compiling a .289 average with four homers and 50 RBIs in 118 games. The 23-year-old is a career .274 hitter in six Minor League seasons, although he has brought that average up over the past two seasons.
Although Nunez has been a shortstop for the large majority of his professional career, he did play 11 games at third this season in Triple-A. He got his first big league crack at the hot corner on Friday night, coming in as a defensive replacement for one inning.
"He's always been a kid with big tools, and sometimes you've got to wait on the tools," general manager Brian Cashman said on Thursday. "The last two years, he's kind of put it all together. ... He's earned the right to be in the big leagues."