Cape Town - Valtteri Bottas says Ferrari have been "surprisingly good" this season, something his new team Mercedes did not expect from their rivals.
Four races into this year's championship and Ferrari are leading the fight for the World title with Sebastian Vettel 13 points ahead of Lewis Hamilton with Bottas a further 10 off the pace.
After last year's win-less campaign it has been a welcome return to form for the Scuderia with Vettel sitting on two races wins while Hamilton and Bottas have one apiece.
"We didn't expect [it] really," Bottas told Autosport of Ferrari's resurgence. "So they've been surprisingly good.
"They had a very good winter and very strong car development since last year. A big step.
"They are managing their tyres at every single track on every Sunday and they've been very much on top of every compound of tyres.
"They've done a very good job on that.
"And I think it's a very good challenge to try and beat them. For sure, we wanted to be ahead.
"We wanted this season to be so far better for us, but I think it's very good in general having the competition.
"It makes us try harder. It makes every single race weekend, every single session very interesting, not only for us, but for everyone."
And although tyres have played a role in the outcome, most notably Ferrari's two wins and Bottas' Bahrain Grand Prix struggles, the Finn reckons over time the tyres will have less of an impact on the race results.
"It's more difficult to master every compound for every tarmac, and how they behave.
"I think it's been always like that in F1, but now that our car with Ferrari is so equal small things like tyres [can decide the outcome].
"In the end, it's the only thing in contact with the car and the ground.
"But my thinking is in the future it's going to be less and less speaking about the tyres.
"Once people and teams learn more about getting everything out of the tyres in the right windows in different conditions, then I think probably everyone is going to be equal in how they handle tyres.
"So there is going to be less speaking about tyres and it's going to be more about the cars, and set-ups and car development."