Nico Rosberg overcame a technical issue to lead the way in opening practice for Sunday's Belgian Grand Prix.
Rosberg had spent much of the first hour sidelined with a power gremlin, but the German gazumped his team-mate Lewis Hamilton with his first flying lap of the morning.
The 30-year-old, who started from pole position here last year, posted a best time of one minute 51.082 seconds to leave him a quarter of a second faster than Hamilton.
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Daniel Ricciardo, a winner in Belgium last year following Rosberg's second-lap collision with Hamilton, was best of the rest, and only marginally slower than the Mercedes pair.
Ferrari are celebrating their 900th grand prix and Kimi Raikkonen, who will now stay with the Italian team in 2016, finished the session in fourth place, over three-tenths of a second quicker than his team-mate Sebastian Vettel.
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The sport of Formula One emerged from its four-week summer hiatus in the beautiful setting of Spa-Francorchamps on Friday.
Famed for its inclement weather, the famous track was bathed in glorious sunshine for the opening session, but there was nothing pretty about Pastor Maldonado's crash.
The session was temporarily suspended after the error-prone Venezuelan lost control of his Lotus and thumped into the wall at Malmedy.
Maldonado was unharmed in the incident but he sustained damage to both the front and rear of his Lotus, and with 30 minutes of the session remaining, he was consigned to the sidelines.
With parts of carbon fibre littering the track, the session was stopped. Rosberg was first out on the circuit after the debris was cleared, and signalled his intent to take the title battle to Hamilton, who he is 21 points behind in the drivers' championship, by charging straight to the top of the time sheets.
McLaren have become accustomed to propping up the rear this season and there will be little respite for the beleaguered team in Spa.
Fernando Alonso and Jenson Button are both set to start Sunday's race from the back of the grid as a result of engine penalties.
Alonso, who finished fifth last time out in Hungary, ended the session in 16th, 2.4secs adrift of Rosberg.
Button, competing in his first race weekend since the harrowing ordeal in which he and his wife Jessica were robbed while sleeping, finished ahead of only the Marussia pair of Will Stevens and Roberto Merhi in 18th.
Elsewhere, Daniil Kvyat was sixth for Red Bull, with Dutchman Max Verstappen seventh. His Toro Rosso team-mate Carlos Sainz was eighth as Force India's Sergio Perez and Valtteri Bottas of Williams rounded out the top 10.