Nova, who started the game, suffered a sprain and bruise of his right ankle, and manager Joe Girardi later revealed that he has been without fill-in closer David Robertson for three days with left ribcage soreness.
Robertson said that he felt soreness after a two-out appearance on Friday against the Rays in a non-save situation, an outing in which he threw just six pitches. An MRI exam is likely to be scheduled for Tuesday morning.
"I'm not really concerned," Robertson said. "I would like to get back out there as soon as I can. But I don't want to go out there and take a risk [and] end up putting myself on the DL for a long period of time. There's a little worry, but I honestly, don't think it's too bad."
Nova had a similar level of concern, though he was dejected after twisting his ankle while coming off the mound to field a Wilson Betemit tapper in Baltimore's half of the sixth inning.
"The X-rays came back negative, so that's a good thing," Girardi said. "Basically, we're going to have to see how he feels tomorrow. I'm sure it's going to be sore where he got hit with the ball, and we're going to have to see how bad he turned it."
Nova said he suffered a similar injury to the opposite ankle last year while pitching for Triple-A Scranton/Wilkes-Barre. He did not miss a start because the All-Star break permitted him extra rest.
"I guess [Tuesday] is going to be worse; you never know," Nova said. "It happened to me last year in Triple-A, and the next day was the bad day. Hopefully tomorrow it won't be like that."
Nova had been hit hard in his outing, surrendering five runs on seven hits in 5 1/3 innings. One of the hits was Nick Markakis' third-inning smash off Nova's right foot, which accounted for the bruise.
Nova said the sprain felt much worse than the bruise, and the righty is hopeful he will be able to take his next turn in the rotation. Girardi said missing a start is a possibility.
"I don't want to miss any of my starts," Nova said. "I hope I can feel better and pitch next time."
The Yankees also had a couple of minor injuries; reliever Clay Rapada had to be helped into the clubhouse with what the team said is a viral infection, and Raul Ibanez left the game after being hit on the right elbow with a Dana Eveland fastball.
Ibanez showed off a bruised stitch mark on his elbow but said he would be available to play on Tuesday.
Robertson moved into the closer's role this month when the Yankees lost Mariano Rivera to a season-ending right knee injury, and the right-hander has made three appearances since then -- a high-wire save, a blown save and Friday's bounce-back outing.
Robertson said that he has been able to play catch as he normally would, but the soreness has forced him to cut back on his weight lifting.
"It's tough now, because the bullpen is kind of thin," Robertson said. "Guys have been pitching a lot of back-to-back days and I haven't been able to step in, help out and pick up some innings. That's where it really hurts."
Girardi said that the team was hoping Robertson's soreness would have disappeared by now.
"We thought it might be a couple of days, but he still felt it today, so we're not taking any chances," Girardi said.
There were indications something was awry as Robertson was passed over not only for the ninth inning, as Rafael Soriano locked down his second save of the year, but also in the eighth, where he had grown comfortable until Rivera's injury necessitated a shift.
Boone Logan and Cory Wade split the eighth-inning duties on Monday, helping to preserve David Phelps' first Major League win. With Robertson out, Soriano -- who saved a Major League-leading 45 games for the Rays in 2010 -- said he is up to the challenge.
"I feel the same as I did in 2010," Soriano said. "They give me the opportunity, and I try to do the best I can."