MONTMELO, Spain — Williams and Ferrari are poised to make a good start to the Formula One season after both finished winter testing with another strong showing on Sunday.
Whether they can challenge champion Mercedes is another issue.
Nico Rosberg may have had a subdued final turn behind his Mercedes, but the German team has given no indication of slippage after dominating last season when Rosberg was Lewis Hamilton's only challenger for the title.
McLaren's Jenson Button, meanwhile, toiled to another session-low 30 laps.
The Australian Grand Prix is in two weeks.