Mercedes' Wehrlein tops rain-hit first day of Austrian F1 test

Wehrlein clocked a time of 1m11.005s to finish 0.187 seconds clear of Force India's Esteban Ocon on a day when rain threatened to extend the test into Thursday.

Rain was falling steadily when the session got under way, with Fuoco and McLaren's Stoffel Vandoorne heading out on full wets for an installation lap.

The track remained empty thereafter before the session was red-flagged at the half hour mark when the rain intensified at the Red Bull Ring.

With conditions not expected to improve until the afternoon, discussions began as to whether to cancel the day's running and extend the test until Thursday.

However, after much deliberation, the decision was taken to run in the afternoon, as the weather began to improve, and instead extend the day's running by two hours.

An hour after the lunch break, Vandoorne broke the silence when he headed on full wets, swiftly followed by Fuoco and Toro Rosso's Max Verstappen.

Conditions improved quickly, with a switch to intermediates soon following and it wasn't long until the track dried sufficiently for dry rubber.

Fuoco, a Ferrari Academy driver who won the 2013 Formula Renault 2.0 ALPS series, clocked up an impressive number of laps.

But with three hours of running to go, the Italian put a wheel on the grass on the approach to Turn 1 and spun, hitting the wall and damaging the front-end of the car.

The Italian finished up fourth, one place behind Verstappen, who completed the most laps of anybody with 97.

More rain fell with one hour to go and though Ocon, Williams' Susie Wolff and Red Bull's Pierre Gasly headed out on a track that soon became dry enough for slicks, the times did not improve.

Gasly ended the day sixth quickest, behind the Lotus of Romain Grosjean, with Sauber's Marciello, who only put his first lap time on the board with three hours to go, seventh.

Vandoorne, who hands the car over to Fernando Alonso on Wednesday, was eighth fastest, with Wolff - who will be in the car for British Grand Prix practice - ninth.

DAY ONE RESULTS: