Ducati’s Jack Miller held off challenges from Yamaha’s factory duo Fabio Quartararo and Maverick Vińales to set the fastest-ever MotoGP lap around Losail as Wednesday’s opening test session drew to a conclusion.

Having led the way for the majority of the evening session, as the first rider to break the 1’54 barrier, the Australian’s dominance looked to be short-lived as Quartararo ramped up the excitement yet again as the session reached its closing half-an-hour.

The Frenchman returning to his electric best with record-breaking pace as he secured a 1’53.263 on his 55th lap, 0.12s under Marquez’s 2019 all-time-best, however, Miller superseded his effort once again, with a breathtaking 1’53.183 on his final effort on fresh tyres.

The start of the final three days of testing saw the teams and riders hit the ground running with a raft of parts ready to evaluate ahead of the opening race of the 2021 season.

A new chassis and slimmed-down front fairing - first spotted on Dani Pedrosa’s bike but seen on Miguel Oliveira’s early on Wednesday - were among the goodies on offer in the KTM garage.

Joan Mir’s crew chief Frankie Carchedi intimated to a comprehensive programme in the Suzuki box via a tweet on Tuesday, stating “many more new and exiting parts to try! Normally it would be split between Valencia, Jerez, Sepang and Qatar test. You know that feeling when you cram your suitcase and have to sit on it to close it. Very important as every tenth counts!”

Both riders seemed to confirm the schedule, as the previously laid-back pair were first out the blocks as the track went green, with multiple areo options among the list of parts ready to analyse.

Pol Espargaro was the man on a mission with three hours to go, hitting the top of the times with a 1’54.272 and two Yamaha’s - that of Franky Morbidelli and Fabio Quartararo - firmly on his tail.

The Spaniard had closed the first test claiming teammate Stefan Bradl was the man to watch, having followed the German’s progress closely both on track and through the data, however, a crash at turn two curtailed the number 6’s progress as the second test got underway, with a neck injury ending his day after just 15-laps.

Bradl’s work was clearly paying off for HRC, however, as all three full-time riders, Espargaro, Alex Marquez and Takaaki Nakagami were all seen sporting the test rider’s new chassis of choice, that used towards the end of 2020 and throughout pre-season, with the ‘2021 chassis’ being packed up rather than run for the remaining days.

Rumours of Marc Marquez’ imminent return have begun to pick up pace thanks to a recent interview where the optimistic eight-time world champ stated “I feel like I can rider soon” however, whether that means in time for opening race is still to be seen.

Multiple manufacturers have already made public concerns over replacement and test rider, Bradl’s, amount of track time before potentially running for the season - depending, of course, on Marquez’ rehabilitation and recovery.

The 31-year-old’s promising and somewhat unexpected positioning towards the top of the times in recent sessions obviously bringing out the complaints - his running at the back would have proven far less contentious.

Ducati’s Jack Miller and Pecco Bagnaia seemed to have well and truly found their feet at the factory team as the pair dominated the times in tandem with two and a half hours to go - Miller becoming the first rider to break the 1’54 barrier, with a blistering 1’53.826 effort - before Yamaha’s Maverick Vińales and Suzuki’s Joan Mir split the duo, relegating Bagnaia to fourth, just four-tenths shy of his team leader.

Ducati appear to be sticking with the new areo package first spotted across the factory machines last week, with Miller expecting to see it on the Desmosedici for race one, in just over a fortnight’s time.

Despite a steady start, Aleix Espargaro was back on form as Wednesday neared its conclusion, slotting his Aprilia into second position for the final two hours of play and the second rider to secure a 1’53 time, before he was outperformed by Johann Zarco - by a mere one-thousandth of a second - moments later.

Ducati’s engine dominance continued to shine across the board, with the satellite Ducati impressing the field as he set the fastest overall top speed, 352.9 kph.

90 minutes to go and it was the younger Espargaro who was back in the limelight as the Honda recorded a stellar 1’53.899 time on his 47th lap, before the 29-year-old promptly returned to the Repsol garage, but it was Miller who retained control of the overall times as the final hour approached.

Miller was initially challenged by Yamaha’s new signing, as Quartararo became the first rider to break Marquez’ 2019 record, before the Australian returned to the top once again with his final attempt of the day, 0.080 faster than the M1, set on his 51st lap albeit with fresh tyres.

Running slightly under the radar, Suzuki’s Mir and Alex Rins concluded the day in seventh and eighth respectively with Pecco Bagnaia narrowly behind, in ninth. Nakagami finished his third day of 2021 testing in 10th, five places higher than teammate Marquez, with the LCR garage unfortunate to endure seven crashes across their two riders thought the day.

Having run in the top-three earlier in the day, Franco Morbidelli sat 11th at the close of play, two places ahead of teammate and academy mentor, Valentino Rossi, who looked more comfortable as he continued to get to grips with his Petronas surroundings.

Circulating for the majority of the day on the fringes of the top-10, over a second clear of his previous best and well into the mid-1’54’s after 56 laps on track, as he concentrated his focus on race pace and long-runs rather than time-attacks.

Splitting the Petronas pair, Oliveira sat 12th at the end of Wednesday’s seven-hours, and best of the KTM effort, with Danilo Petrucci finishing 17th, Brad Binder 20th and Iker Lecuona 21st.

Enea Bastianini continued his run as fastest rookie in 14th, five places clear of Pramac’s Jorge Martin, with Luca Marini behind in 22nd while Lorenzo Savadori finished as the final full-time rider, in 25th just shy of three-seconds off the pace.