Lewis Hamilton's hopes of a fourth successive pole position at this stage appear forlorn as the Briton finds himself some distance behind the trail being blazed by Sebastian Vettel.
In final practice for the Belgian Grand Prix, Vettel again emerged quickest after topping the timesheet following Friday's two 90-minute sessions.
In the closing hour-long run ahead of qualifying, the reigning world champion posted a lap time in his Red Bull of one minute 48.327secs, going a second faster than on Friday.
As for Hamilton, who has been on pole in the last three races in Britain, Germany and Hungary, taking the chequered flag at the latter for the first time with Mercedes, he finished a lowly 12th.
It means the 28-year-old, who was seven tenths of a second adrift of Vettel, has failed to finish in the top 10 in any of the three practice sessions.
It would appear Mercedes' Spa-specific package, something which all teams provide for this race given the high-speed demands of the track, is struggling to show the pace previously seen by their car.
Team-mate Nico Rosberg was down in ninth, 0.666secs adrift of Vettel, whose nearest challengers for pole to date appear to be Ferrari's Fernando Alonso and Red Bull team-mate Mark Webber.
Alonso, who desperately needs to start closing the 39-point gap to Vettel, was a tenth of a second down, with Webber two tenths off the pace.
The leading trio were surprisingly followed by Toro Rosso's Jean-Eric Vergne and Felipe Massa in his Ferrari, while McLaren's Spa package appears to be working well as Jenson Button was half-a-second back in sixth.
Esteban Gutierrez, yet to score a point for Sauber in his debut F1 season, was seventh ahead of Lotus' Romain Grosjean, with team-mate Kimi Raikkonen 10th, the duo either side of Rosberg.
Force India's Paul Di Resta was 15th, nine tenths of a second adrift of Vettel and a tenth down on team-mate Adrian Sutil, who was 13th.
Max Chilton has so far struggled in his Marussia, with the Briton at the rear again over five seconds down, but more crucially 1.2secs behind team-mate Jules Bianchi.
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