CLEARWATER, Fla. -- If you looked at the calendar and followed the days that Aaron Nola has pitched this spring, it is clear the Phillies planned to give him the ball on Opening Day in Miami, even if they never formally announced it.

That plan might be in jeopardy.

Nola missed Monday afternoon’s start against the Yankees in a Grapefruit League game at Spectrum Field because of the flu. Nobody knows how much time he might miss, but it could push back his first start from the March 26 season opener at Marlins Park.

“It’s something we’re going to have to look at,” Phillies manager Joe Girardi said after a 3-1 victory over the Yankees on Monday. “Like, does it get him off his day that he was supposed to pitch to start the season? Possibly. I don’t know. We’ll have to see.”

Girardi said he does not expect Nola back with the team until Thursday at the earliest, and he is unlikely to pitch that day. If Nola pitched on Monday, he would have made two more starts before the end of the spring. If he pitches Friday at the earliest, he would fall one start short before Opening Day. It wouldn’t be the worst thing in the world, but he might be limited with a pitch count.

“Then maybe look at it that way -- he’s just not built up as much as he would be,” Girardi said. “Again, a lot of it depends on when we get him back.”

Another option would be the Phillies could pitch Nola three more times before camp breaks, then have him face the Marlins over opening weekend.

If Nola is not the Opening Day starter, new Phillies right-hander Zack Wheeler could be next in line. Wheeler has been following Nola’s turn in the rotation this spring, and he is scheduled to pitch Tuesday afternoon against the Twins at Spectrum Field.

Nola, 26, has made three starts this spring. He has struck out nine and allowed 13 hits, four runs and one walk in eight innings.