Now that Andy Pettitte has decided to call it a career, the 2011 season just got a whole lot more — let’s say interesting — for the Yankees.

With Pettitte gone, the Yanks’ will likely open with a rotation of some combination of CC Sabathia, A.J. Burnett, Phil Hughes, Sergio Mitre and Ivan Nova.

That quintet doesn’t exactly scream postseason-bound, does it?

There are others in the mix for those back two spots, including former Cy Young winner Bartolo Colon, the once-promising Mark Prior and journeyman Freddy Garcia.

Still, even with those three in tow, the absence of solid arms in two fifths of the rotation could make for a very intriguing spring training for a few Yankees farmhands.

With a good showing at camp, kids like Andrew Brackman, David Phelps, Adam Warren, D.J. Mitchell, Hector Noesi, Dellin Betances and Manny Banuelos could position themselves for a midseason call-up.

A scout I spoke with yesterday said that he doesn’t believe any of those farmhands is ready now, however, so the veterans, retreads and Nova will have to hold the fort for the time being.

One idea the scout suggested was a sort of tag-team fifth spot throughout the course of the season.

The idea would work something like this:

From Opening Day through the end of May, Mitre, Colon, Garcia or Prior would take the ball every fifth day.

Then, from June until the start of August, a prospect would get his feet wet in the big leagues.

After his two months were up, that youngster would relinquish the ball to another farmhand for the duration of the season.

To me, that sounds like a pretty viable solution on a couple of fronts.

First, it helps avoid a Joba-like shuffle to and from the bullpen for someone the Yankees have spent years developing as a starter, something fans certainly don’t want to see happen again.

Additionally, it doesn’t overexpose either prospect long enough for the league to get a good book on him.

The glaring weakness in the plan, however, is that it pins a rookie with 20 percent of the team’s starts down the stretch, which would be especially troubling if the team were to find itself in playoff contention.

If that’s the case, though, you can the Yankees will swing a deal to avoid that kind of scenario.

The bottom line is: Because of Pettitte’s retirement, this season represents the first time in a very long while that an untested prospect has a chance to win a spot in the rotation out of camp.

If that happens, this summer will be remembered more as a fond beginning than a bittersweet ending.