Rookie Marc Marquez fired a further warning shot to his title rivals with a peerless performance in opening practice for the Indianapolis MotoGP.
The young Repsol Honda star, winner of the last two races, concluded his first ever MotoGP track session at the unique infield circuit with a 0.3s advantage over Cal Crutchlow.
Englishman Crutchlow, newly confirmed at Ducati for 2014, popped into second place as the chequered flag was waved.
Prior to the Monster Yamaha Tech 3 rider's late effort, Marquez had been 0.480s clear of Factory Yamaha's reigning champion Jorge Lorenzo, who finished the session in third.
Triple MotoGP race winner Marquez starts this weekend with a 16 point lead over team-mate Dani Pedrosa and a 26 point advantage over Lorenzo. Marquez's best FP1 lap time was 1.7s behind the official race lap record, set by Pedrosa last season.
Pedrosa and Lorenzo have used the summer break to rebuild their fitness from collarbone injuries. Their fractures are yet to fully heal, but both are much stronger than a month ago at Laguna Seca, when they braved the pain to claim fifth (Pedrosa) and sixth (Lorenzo) places.
Lorenzo, riding with a special Green Mamba snake helmet, led the session at the halfway stage before Marquez took control. Pedrosa made a more discreet start to the weekend, finishing in seventh place and 0.8s behind Marquez.
Between Lorenzo and Pedrosa on the timesheets were Stefan Bradl, Valentino Rossi and Alvaro Bautista.
Laguna Seca debut pole and podium finisher Bradl - newly confirmed at LCR Honda for 2014 - had led the session on several occasions, but was ultimately left 0.6s from Marquez. Factory Yamaha star Rossi and Gresini Honda's Bautista were both within one-tenth of Bradl.
Behind Pedrosa, factory Ducati team-mates Andrea Dovizioso and Nicky Hayden, plus Tech 3 rookie Bradley Smith, completed a top ten covered by 1.6s.
Spots of rain during the previous Moto3 practice session raised the risk levels this morning - the three different types of asphalt present around the rarely-used circuit notorious for catching out riders even in the dry.