Haas could be about to leap off the very back of the grid and into Formula 1's tightly-packed midfield.
McLaren finished fourth overall behind the 'big three' teams last year, but boss Andreas Seidl admits it might be a struggle to repeat that in 2022.
"We have no idea where exactly we stand," he said. "Maybe we're fourth, maybe we're not."
The Woking-based team had high profile brake problems in Bahrain testing, but also clear is that some teams have emerged with particularly strong packages for the new era of regulations - particularly those with Ferrari power.
In the new Haas, both Mick Schumacher and his newly-installed teammate Kevin Magnussen were conspicuously fast last week on every type of tyre compound.
There are, however, reliability concerns.
"If the last day of testing had been a grand prix, we would have retired three times," said team boss Gunther Steiner.
But from a pace perspective, McLaren's Lando Norris is concerned.
"At the moment I'd say there are the three teams that look faster than the others, but the difference between the rest is not so big - from McLaren to Haas," he said.
"Haas looked very good actually, which is a big surprise given how far behind they were last year. I think we should be prepared to fight them both in qualifying and the race," Norris added.
Mick Schumacher agrees that he has a much better car with which to tackle his second year in Formula 1.
"We didn't drive as much as we would have liked," he told RTL after the Bahrain test, "but it's about whether we're fast or not - and we're fast!"
