Heat gives Cummins pause for thought ahead of Test toss

The series is delicately poised at one-all and the home side must break the deadlock over the last two Tests in Melbourne and Sydney to regain the Border-Gavaskar trophy.

Pat Cummins was unsure on Christmas Day what call he will make if he wins the toss at the MCG. (James Ross/AAP PHOTOS)

Cummins praised the MCG wicket, which is certain to provide early life for the fast bowlers, but will assess the conditions on Thursday morning before having the toss with Indian captain Rohit Sharma.

"I will see how the heat changes it - I don't know, really," he said of the Test pitch.

"We'll get to the ground (on Boxing Day) and assess, but it looks like a good wicket.

"It's another layer ... you look at the pitch, you get a bit of a sense of what the day is going to feel like and you make a decision.

"I don't think it scares us too much, but we'll wait and see, 39 can get pretty hot."

Sam Konstas has been the centre of attention ahead of this match and the Australian 19-year-old will make his Test debut in the cauldron of the Boxing Day Test.

Cummins was 18 when he made his Test debut and he has impressed on Konstas the need to enjoy the moment and not be overawed.

"There's a level of naivety, that you just want to go out and play, like you did when you were a kid in the backyard," he said.

"You always want to do well. I was saying this to Sammy the other day, I remember as an 18-year-old thinking 'I got a lot more leeway, because I was young' - almost publicly.

"I almost felt like if I didn't have a great game, it wasn't my fault, it was the selectors' fault for picking me ... they're the idiots who picked an 18-year-old."

But there is a limit to how much freedom Konstas will have as a care-free teenager.

"In my debut I remember trying to hit (South African bowler) Dale Steyn over his head for runs and I just thought that made sense at the time," Cummins said.

"I look back and it's like, geez, I would have been crucified if that didn't come off."

Travis Head, Australia's most important player, passed a Christmas morning fitness test and will play, while Scott Boland replaces injured paceman Josh Hazlewood.

Boland returns to his home ground and the venue of his famous Test debut when he tore through England with 6-7.

"Whenever he gets his chance, he steps in and looks like he's one of the best bowlers in the world," Cummins said of Boland.

"I'm expecting much the same here. He loves bowling here, he's obviously played probably more than anyone else (in our team) at the MCG.

"It was pretty awesome that even with an unfortunate injury like Josh's, you can have someone like Scotty to come in seamlessly."

Indian captain Rohit Sharma said on Christmas Eve his knee was fine after he suffered a heavy knock while batting on Sunday.

The tourists have fond memories of the MCG, winning their last two Tests there.