GREEN BAY, Wis. -- Aaron Rodgers was stunned that he pulled a calf muscle in his left leg early in Sunday's game against the Tampa Bay Buccaneers. He figured all the liquids he drank to combat the flu in the days before the game would've protected him from any muscle pulls.

Aaron Rodgers says he suffered a calf injury early during the Packers' win Sunday, but does not think it will be a factor going forward. David Manning/USA TODAY Sports

But Rodgers felt it on the second series of the Green Bay Packers' 20-3 win on Sunday, and it impacted him the rest of the game.

"I battled the flu the last couple of days pretty bad, and that's why I was surprised I hurt my calf because I hydrated like no other," Rodgers said. "I had a great hydration test this week and was drinking a ton of water before the game. Unfortunately the calf kind of gave up on me there."

Rodgers walked out of the locker room slowly on Sunday afternoon after the game but did not think the injury would be a factor in next Sunday's game against the Detroit Lions at Lambeau Field, where the NFC North title will be decided.

"It's too early to give a 100 percent guarantee, but it would definitely take a lot to hold me out of that game," Rodgers said.

Several members of the Packers offense said they weren't even aware that Rodgers had pulled his calf. However, coach Mike McCarthy said he changed his play-calling plan, leaving Rodgers in the pocket far more than usual.

"I think really the last couple days, you see what kind of warrior he is," McCarthy said. "He's battled whatever illness he's had the last couple days, and then goes out and strains his calf the first, second series, and didn't want come out. I was probably affected by it more than anybody with some of the play calls. Just a gritty, gritty performance by Aaron."

Rodgers finished 31-of-40 passing for 318 yards and a passer rating of 108.1, and the Packers clinched a playoff spot for the sixth straight season. But Rodgers didn't throw a touchdown pass until he hit Jordy Nelson for a 1-yarder with 2:45 left in the game.

"It got really tight about halftime," Rodgers said. "Came in and got a little treatment and it loosened up a tad but it was still pretty tight, and I had hard time running. But I was able to move kind of in short segments in the pocket, which was all I needed to do today."