Retallick has been out of Super Rugby for eight weeks, recovering from a wrist injury.
Retallick said it had been tough watching on but he had used the time wisely.
"Eight weeks has been kind of a good in hindsight, especially around my fitness and my body and stuff like that. So yeah I don't think fitness should be an issue. Thanks to the trainers here, for the last eight weeks I've just been running up and down the sideline," he said.
The 28-year-old said he had been doing a lot of skill work in the last couple of weeks.
"I was in Fiji doing a lot of the skill work. I pretty much did a full week of training there [but] it was slightly more controlled so I'm pretty confident in terms of that. I guess it'll just be dealing with things under pressure maybe that you slightly can't get in training, but I'm pretty happy with where I've got to skill wise and physically."
Retallick said it was important at training this week to replicate the pressure the Rebels brought at line-out time.
He said the Melbourne outfit were very disruptive.
"We've hopefully come up with a good plan. I'll try not to give too much away but if we get there and speed the game up, I think that's where the Crusaders came out on top of them, when they speed the game up and kept the ball in play. So hopefully we don't have to deal with too many lineouts and keep the tempo up."
Retallick said he was impressed with the way the Chiefs had been playing.
"Against the Reds we made an outrageous amount of tackles, I think it was 230 or something. Then against the Crusaders to come back from 20 nil after 20 minutes down, to show that fight there's no question [in] the heart and commitment. Ideally we wouldn't let a team get to 20 nil after 20 minutes, but we can score tries and we can make tackles so if we can do that for 80, it's do or die for both teams this week so that's what we'll need to do."
The Chiefs meet the Rebels this Friday in Melbourne.