Sabathia was pitching in the top of the third inning during the announcement. The man he was replacing, Shields, came out to pitch the bottom of the third.
The 30-year-old Sabathia will be making his fifth All-Star appearance, but, like Shields, he will be unavailable to pitch. He will not be making the trip to Phoenix's Chase Field.
The 26-year-old Robertson is one of eight Yankees players to make this year's All-Star Game, and the only one making his first appearance.
"I'm just a little surprised," Robertson said. "It seems like this whole season has crept up on me. It came down to this point. "
With his strikeout stuff and ability to wriggle out of jams, Robertson has been a cog in a Yankees bullpen decimated by injuries. He has 56 strikeouts in 35 1/3 innings, to go along with a 1.27 ERA. The 14.26 strikeouts per nine innings are the most among any pitcher with at least 30 frames this season. Robertson has walked 23 batters, but he has yet to allow a home run in 2011.
After hearing the news from Girardi, Robertson ran into the clubhouse to call his wife, Erin. The late nature of the announcement may lead to some scrambling, but Robertson doesn't mind.
"I'd pretty much given up," Robertson said. "I thought if it hadn't happened by now, it isn't going to happen."
Robertson will join Cano, Russell Martin and Curtis Granderson at Phoenix's Chase Field.
Alex Rodriguez, Derek Jeter, Mariano Rivera and Sabathia are also All-Stars, but will not make the trip.