Barring an agreement, Rodriguez's appeal would be heard by arbitrator Fredric Horowitz.
Adding to the drama: The 38-year-old Rodriguez, a three-time AL MVP, was due to rejoin the Yankees for their series opener at the Chicago White Sox, his first big league appearance since last October's playoffs. He's been rehabbing since hip surgery in January.
"He's in there, and I'm going to play him," Yankees manager Joe Girardi said Sunday after New York's 6-3 loss at San Diego.
Yankees outfielder Curtis Granderson was excited A-Rod could play during an appeal.
"I want him back with us. This is arguably one of the best hitters of all time," he said. "Having him in the lineup is obviously going to be very positive for us."
New York is a season-high 9½ games out of first place in the AL East and 4½ out in the race for the second wild-card spot.
"We're going to be happy to see him back in the lineup, especially the way we've been playing," second baseman Robinson Cano said. "He can come up and help us win some games."
All-Stars Nelson Cruz of Texas, Jhonny Peralta of Detroit and Everth Cabrera of San Diego were among those who could get 50-game suspensions from the probe, sparked in January when Miami New Times published documents linking many players to the closed clinic in Coral Gables, Fla.
Many players were expected to agree to penalties and start serving them immediately, but an appeal by a first-offender under the drug agreement would postpone his suspension until after a decision by an arbitrator.
Milwaukee outfielder Ryan Braun, the 2011 NL MVP, agreed July 22 to a 65-game ban through the rest of the 2013 season for his role with Biogenesis.