Sidney had been plagued by the ailment all week, and coach Rick Stansbury determined Saturday morning that the 6-foot-10 junior wouldn't be able to play.
"He said he couldn't go, so that's kind of where we left it at," Stansbury said following his team's 65-55 loss.
The Tigers outscored MSU in the paint, 34-24, and also won the rebounding battle, 36-31. That was despite starting center Rob Chubb being limited to 17 minutes by foul trouble.
Arnett Moultrie, battling a left shoulder injury, had 16 points on 6-of-15 shooting and 11 rebounds for State.
Sidney had scored 17 points in the teams' first meeting.
"Everybody knows he's probably a (NBA) guy," Auburn's Frankie Sullivan said of Sidney. "His presence is felt when he's on the court."
It was the fourth game this season Sidney has missed due to injury, the first in conference play. But Stansbury didn't want to use that as a reason for the loss.
"We don't make no excuses. We had a game to play, and we had a team we lined up with, and I feel good with what we lined up and fought with."
Off the mark
MSU's tough shooting night was summed up in Rodney Hood's struggles.
The freshman guard made just 3 of 12 shots and 1 of 8 from behind the arc. He missed a three with 2:09 to go that could have made it a one-point game.
"I'd line Rodney back up and let him shoot the same shots again," Stansbury said. "That wouldn't faze me. He's shot the ball well all year long."
Sullivan's big shot
Prior to the game, Sullivan was honored for reaching 1,000 career points the previous game. The junior guard didn't have his best shooting night - 6 of 14 overall, 2 of 6 from three - but hit a big one late.
Auburn led 56-52 when Sullivan drove and lobbed a shot high in the air. It dropped through with 1:39 to go, and MSU never got any closer.
"It was definitely a tough shot. I have to give that to God, because it was all luck," Sullivan said with a smile.
Losing to Auburn, which had dropped three in a row entering the game, does MSU no favors in the eyes of the NCAA tournament selection committee.
Auburn entered the game with an RPI rank of 134, MSU at 50, according to RealTimeRPI.com. Up next is a home date with No. 1 Kentucky on Tuesday.