The Lotus driver told Sky Sports News: "It's going to be difficult to be better than third! The front row will be all Red Bull, but you never know. We have some rain coming tomorrow as well.
"They were the strongest cars at the end of last year. There's no change in the regulations that would mean they wouldn't be the strongest today. We have to work to try to catch them.
"On race pace we know we are strong. The car is feeling more or less the same as last year, which is a good point. It's good to have good race pace but we still need to improve a little bit for qualy."
The 26-year-old started last year's race in Melbourne from third following a McLaren lockout.