Carlos Sainz Jr. believes Haas are half-a-second quicker than everyone else in the midfield battle, including the Spaniard's team McLaren.
Haas were the quickest in the midfield battle in Australia, with Kevin Magnussen recording a P6 finish in Melbourne and Romain Grosjean in a good position prior to the pit-lane drama for the American outfit.
Sainz was the first retirement at Albert Park following an MGU-K failure, with McLaren just one of two teams, with Williams, who didn't record a single point in the season-opener.
"The only one that could escape that it is the Haas as they are a bit too far ahead in the midfield for everyone else," Sainz told reporters in Bahrain. "That is the only bad thing compared to last year, that the Haas is a bit too far away compared to last year.
"It is more than half-a-second, to close a gap of half-a-second even in a high development rate this season it would be a very difficult task.
"They won't standstill so you need to develop at least seven or eight tenths which is a lot of lap-time. My big estimate is it is going to be very difficult to end the year in front of Haas in qualifying. I wouldn't say in a race but in pure pace it is going to be very difficult for anyone.
"I don't look at numbers as much as the engineers, I just do my guesses looking at lap-times and how good their lap-times were compared to mine or my team-mate's. I did a rough calculation, this is not an exact number. Half-a-second is a lot, but we will try."