Cox was 10-for-13 for 154 yards after replacing starter Matthew Stafford, who was 8-for-16 with 76 yards and looked like a true freshman for the first time.
"I want to be real clear, I'm not disappointed in Matthew at all," Richt said. "It was just a matter of saying, ‘We need to get this thing going.' Sometimes you just need to get that starter out of there."
Cox responded by throwing for two touchdowns and leading the Bulldogs to a 14-13 come-from-behind win over Colorado. The offense managed just 89 yards under Stafford, who was the victim of four dropped passes and some suspect blocking.
"I don't think (Stafford) played poorly," quarterbacks coach Mike Bobo said. "We obviously had a couple drops. The offense was really just stagnant. We needed a change offensively, a spark, and we felt like Joe could give us that spark."
A Sanford Stadium crowd that had wholly supported Stafford through three games cheered loudly when Cox entered with just less than three minutes left in the third quarter.
"To come off the bench like that is not easy to do, but he did it," Richt said. "He played outstanding in that situation."
Stafford was despondent on the sideline immediately after being yanked but had nothing but positive things to say about Cox after the game.
"Happy with the win, man," he said. "(Cox) is a fiery guy, and he got in there and did an awesome job, completed a couple balls and swung the tide."
Stafford was confused at times by a defense that did a good job of mixing up coverages and throwing things at Georgia that the Bulldogs hadn't seen, Richt said.
"I know that I didn't play my best game," Stafford said. "I'm getting kind of tired of saying that, but these type of games are going to happen."
Neither Stafford nor Cox had a guess about who will be the starter Saturday.
"If he starts me, he starts me," Cox said. "If I sit on the bench with a hat on, I'm going to wear that hat proudly. Whatever Coach Richt wants to do in regards to me, I'll do it. I know if Matt had stayed in, he would have done the best he could, and I have all the confidence in the world he would have (led a comeback), too."
The job of determining who will start against Ole Miss in Oxford, Miss., will begin today when the coaches look at the film from the game.
"We'll look at the film and try to be real certain about what happened," Richt said. "I imagine there'll be some computers blowing up with people hitting the Internet speculating about who will play quarterback."