Fernando Alonso set the early pace in second practice at the Australian Grand Prix before rain affected the majority of the session.
The Aston Martin driver was 0.445 seconds quicker than Ferrari's Charles Leclerc. Red Bull's Max Verstappen was third fastest, 0.615secs off the pace.
Verstappen topped the first session, run in dry conditions, ahead of Mercedes driver Lewis Hamilton.
Hamilton was only 13th in the second, with team-mate George Russell fourth.
Hamilton's dry-weather running was curtailed by a decision to pit for set-up changes in the front suspension.
Verstappen also appeared to be unhappy with his car balance in the dry, the world champion running wide over the grass at the first chicane before setting his fastest time.
It was the continuation of a scrappy day for Verstappen, who leads the world championship by one point from team-mate Sergio Perez after the first two races of the season.
Perez's attempts to set a quick time in the second session were torpedoed by slower cars getting in his way on each of his laps and he ended up seventh fastest.
The forecast is for dry weather for the weekend's running.
In the first session, Verstappen lost control of his Red Bull at Turn Four towards the end of the hour's running on his first lap on a second set of soft-compound tyres.
Verstappen was 0.433secs quicker than Hamilton in that session.
Perez also lost control of his car on his run on soft tyres in the first session, in his case at Turn Three. He ended up with the third-fastest time with a lap on medium tyres.
Team principal Christian Horner admitted in the break between the sessions that neither Red Bull driver had been happy with their car in the first hour.
Alonso was fourth fastest in the first session, ahead of the Ferraris of Leclerc and Carlos Sainz.
McLaren's Lando Norris was seventh and eighth in the two sessions.
Norris' team-mate, the Australian rookie Oscar Piastri, was consistently fast in the wet conditions later in the session when many drivers explored the track on intermediate tyres.
Williams driver Alex Albon set the fastest time on intermediate tyres as the track began to dry towards the end of the session.
The first session was punctuated by a 10-minute red flag caused by the failure of F1's GPS system, which tracks car position on track.
Governing body the FIA said the session needed to be stopped "for safety reasons with teams not being able to monitor car position and closing speed".