Still, Coach Mark Richt said he's pleased with Shockley's progress.
"He hasn't had a lot of success the last few games, but I don't think that's an indication of how ready he is to play," Richt said.
Any time off Greene takes this week to rest his hyperextended right knee means first-team snaps for Shockley, who normally has to wait for Greene to take his turn in drills.
"It was good to see (Shockley) be the first to do it," Richt said. "It's great for him. He practiced beautifully (Tuesday)."
Shockley has maintained a positive attitude despite his limited playing time and limited success, Richt said.
"He's a good man, he really is," Richt said.
INJURY UPDATE: Starting running back Tony Milton is doubtful for the Oct. 4 Alabama game, Richt indicated Wednesday. Milton has a calcium deposit in his leg that has kept him out of the last two games.
"His recovery is slow," Richt said.
Greene returned to limited action on Wednesday although he didn't participate in any contact work. He looked good enough that Richt said he would play if the Bulldogs had a game this weekend. Tight end Martrez Milner sat out due to a slightly sprained ankle but expects to be back soon. Wide receiver Mario Raley (foot) said he probably will return to practice Tuesday.
AREA OF NEED: When the Bulldogs lost Milton, they lost their only dependable blocking tailback.
"Milton's one of the best blocking tailbacks I've ever been around," Richt said. "He hurt people. He hits you like a hammer. Not many people came back for more with him. He's just a tough guy."
Milton's absence was felt particularly hard during Saturday's 17-10 loss to blitz-happy LSU. Richt was disappointed with the blocking of Michael Cooper, Tyson Browning and Kregg Lumpkin in that game.
He told that trio before Wednesday's practice that they were competing for the top job and playing time on every practice snap.
"I don't know who's No. 1 right now," he said. "They all see the urgency of getting the job done," he said. "They all gave a whole lot better effort. They all made strides for sure."