Next week, Mackey, a junior quarterback, is aiming for his second win in as many starts.
But unlike last week, when the opponent was Fresno State, Ole Miss is back to Southeastern Conference play. And the toughest part of its schedule. And the beginning of a three-game gauntlet against Alabama, Arkansas and Auburn.
The Rebels, who are off this week, host Alabama Oct. 15 at 5 p.m. CT on ESPN2.
"Alabama's just Alabama," Mackey said. "They've got a real good defense from the d-line to the secondary to the linebackers. There are still, I'm not going to say weaknesses. But, you know, they ain't Superman. They can be beat."
For the first time in months, Ole Miss entered a practice week with one quarterback as the unquestioned starter. Zack Stoudt started three games this season, while Barry Brunetti opened the year under center in a 14-13 loss to BYU.
"I was just staying cool. I don't try to let that starting stuff go to my head and all that," Mackey said of the practice week. "I just try to just be myself out here; still just be playing around, clowning with everybody. Just making everybody feel good."
"Getting confidence. Getting better," Ole Miss head coach Houston Nutt said of Mackey. "Making good decisions and throwing the ball well. Just see confidence."
Mackey was 8 of 18 for 214 yards, one touchdown and no interceptions against Fresno State, a 38-28 win.
Ole Miss is 2-3 overall on the year, with two of its three losses against league opponents. The Rebels have lost 10 of their last 11 conference games.
Alabama, meanwhile, is 5-0 and 2-0 in SEC play. In the latest polls released Oct. 2, the Crimson Tide moved up to No. 2 in the Associated Press Top 25 and dipped one spot to No. 3 in the USA Today Coaches' Poll. Alabama and Vanderbilt meet Saturday in Tuscaloosa.
"I think he can work on just what he did this week," Nutt said. "He's been in a good rhythm, getting rid of the ball. Gotta do the same thing and maybe even a little quicker, ‘cause you're going to be playing the best defense in the country. I think after watching film, he understands that. He's just building off last week, and he'll continue to get better."
One reason Mackey was inserted into the starting lineup was because of his ability to extend plays. Ole Miss has struggled to protect up front. Mackey is a capable runner. He had 35 rushing yards on five carries vs. Fresno.
In its last 24 games, Alabama has allowed just 20 touchdowns and 224.2 yards per game to its opponents. Opponents have averaged a paltry 8.4 points per game.
"I ain't going to doubt myself. But at the same time, we've got to be one as an offense to win that game against Bama," Mackey said. "Everybody's got to be on the same page. We can't have no penalties, no missed assignments. It's got to be almost a near-perfect game.
"I feel real comfortable starting right now. Going out there, still being a leader."