Third and final Formula 1 practice for the Italian Grand Prix was a near-total washout, with Williams duo Felipe Massa and Lance Stroll fastest of those to set a time.
Showers overnight were followed by heavier rain on Saturday morning at Monza, leading to the cancellation of GP3 qualifying.
F1 race director Charlie Whiting then delayed the start of F1 practice "indefinitely" as the risk of aquaplaning was high.
The clock for the 60 minute session started on time, as there has to be a two-hour gap between the end of FP3 and the start of qualifying.
The safety car headed out several times to assess the track, and at just past the halfway point deemed the conditions had improved.
The session started with 16 minutes remaining, with Red Bull's Daniel Ricciardo the first driver to head out to brave the puddles on a set of wet Pirelli tyres.
All 20 drivers eventually headed out to assess the track conditions, but only seven completed timed laps.
The conditions remained treacherous, with Toro Rosso duo Carlos Sainz and Daniil Kvyat locking up on the run to the first corner and missing the first chicane.
Sainz completed the most running, with five laps, while Massa topped the times with a 1m40.660s to end the session just over two-tenths faster than Stroll.
Nico Hulkenberg, Sainz, Jolyon Palmer, Marcus Ericsson and Kvyat were the other drivers to complete timed laps.
The conditions meant teams were unable to carry out the usual qualifying simulations.
|4||Carlos Sainz Jr.||Toro Rosso/Renault||1m41.515s||0.855s||5|
|7||Daniil Kvyat||Toro Rosso/Renault||1m45.033s||4.373s||4|
|8||Daniel Ricciardo||Red Bull/Renault||-||-||1|
|9||Max Verstappen||Red Bull/Renault||-||-||1|
|16||Esteban Ocon||Force India/Mercedes||-||-||2|
|19||Sergio Perez||Force India/Mercedes||-||-||1|