Ferrari won the first two races of the year before a smart Red Bull strategy allowed Daniel Ricciardo to take victory in China last weekend, meaning the all-conquering Mercedes team of the last four seasons is yet to triumph in 2018.

Lewis Hamilton and Mercedes were the benchmark in Australia but a safety car handed victory to Sebastian Vettel, who was the pacesetter in Bahrain and China.

Raikkonen said it was "very hard to say" what the competitive order is.

"If you ask anybody, it's a bit tricky to give you an answer," he said. "I think a lot of the end result [in China] depended on whether you had better tyres t han others, when you could offset yourself to the others.

"Obviously, it's a big part of the game, and it made a big difference, [as did] the safety car.

"Pure speed, with everybody on the same tyres in a race… it's difficult, very difficult, to say.

"I think it's nice like that, for everybody to watch, because nobody really knows.

"Everybody would love to know but nobody really [does] because it changes from race to race and such a small difference makes a big difference in the end result.

"You just have to wait and see. It might change from race to race, and who runs what tyres."

Mercedes and Ferrari have both displayed benchmark performance in qualifying and race trim at some point across the first three races, but Red Bull is the unknown factor because its first two grands prix were compromised.

In Australia Ricciardo earned himself a grid penalty and Verstappen had a messy race, and factors outside the team's control hurt it again in Bahrain where Ricciardo retired on lap two with a Renault energy store failure and Verstappen clashed with Lewis Hamilton.

Ricciardo agreed with Raikkonen that "we don't really know" the full picture.

"It's still hard to say, we were really quick on the softs but at that stage everyone else was on mediums," he said.

"At the beginning of the race on ultrasofts we could hang with Lewis and Kimi, but they were on softs. We haven't really had a good comparison. At times, the end of the race in Melbourne and China, we were very strong.

"The initial laps, when the car is still heavy with fuel, we can be better. We're not too far off but there are still some areas we can be stronger."