Danish defender Agger missed Monday night's 2-2 draw with Swansea City because of a rib injury while fellow backman Kelly is recovering from a knee problem.
Rodgers says he will continue to monitor the twosome ahead of this weekend's home clash with Southampton.
"We'll see how he is in the next 24 hours," Rodgers said.
"It's too early to say if he'll be ready for the weekend or not. It was just unfortunate it happened the day before the game. We're hopeful he'll be fine by the weekend."
Regarding Kelly, he added: "He has been excellent in training. He is very focused on his fitness and sharpness. In the game the other night he was excellent.
"I'm looking forward to having him back and thankfully it has all gone well so far."