Fabio Quartararo continued his fine pace over a single lap to pip Marc Marquez and sit top of the MotoGP timesheets after FP2 at the Czech Republic Grand Prix.

A late effort from Petronas Yamaha's rookie star, who has claimed pole in two of the last three races, saw him beat reigning world champion and standings leader Marquez by just 0.023seconds.

Friday's action in Brno took on an added importance with rain expected during Saturday's FP3, meaning these times are likely to prove crucial in determining the 10 riders who seal automatic progression to Q2.

The Ducati machines looked competitive with Jack Miller and Andrea Dovizioso setting identical times 0.269secs behind Quartararo, closely followed by in-form Maverick Vinales in fifth and Suzuki Ecstar's Alex Rins.

Valentino Rossi - who overcame a mechanical issue - and Danilo Petrucci are also in the top 10 as things stand, the latter narrowly edging Joan Mir into 11th, while Takaaki Nakagami crashed in FP2 and had to settle for 12th.

Dovizioso, who sits second in the riders' championship and won last year's race at this circuit, had topped FP1, with Marquez also coming second in that stint.

But every rider went faster in a competitive later session, with just 0.423s covering the top six and under a second between the 13 fastest riders on the track.

Repsol Honda star Marquez has won five of the nine races this season and added three second-place finishes, giving him a comfortable 58-point advantage over Dovizioso going into this event, the first since MotoGP's mid-season break.