Kimi Raikkonen says the pecking order behind the top three teams is "a big mystery". Some are predicting that Alfa Romeo is now ready to take on Renault to be the 'best of the rest' in 2019, but the Finn says it is far from clear cut.
Alfa impressed during the first pre-season test, but they ended the fortnight of testing as just the eighth-fastest team, with only the beleaguered Williams team and a Racing Point squad using many 2018 parts behind them.
Raikkonen admitted that Alfa had not hit their potential in Barcelona and says the lie of the land in the midfield is a total unknown.
"It's unclear to us where we stand," Raikkonen, who has switched to the former Sauber team from Ferrari, said.
He admits the 2019 car is a "solid package, but we still need to improve a few things".
"The mood is good and there is nothing negative, but like everyone else we want to improve. There is always something to improve," Raikkonen added.
Among the midfield pack is Haas, with its boss Gunther Steiner saying it would be "a dream" for the American team to finally end a race on the podium.
"But if everything goes well, nobody can reach the podium except for the top three teams," he said.
Sergio Perez, who drives for Racing Point, said: "We know we are not the fastest but not the slowest in the middle group of teams.
"At the same time, the difference between the fastest and the slowest of those teams is less than half a second," he added.