Marco Bezzecchi, using a 2022-spec Desmosedici, stole the limelight with a late lap of 1m 58.470s, with Aprilia's Maverick Vinales then moving into second place to break what had been an all-Ducati top three for much of the day.

New factory Ducati rider Enea Bastianini, team-mate and reigning champion Francesco Bagnaia, plus Pramac's Jorge Martin all took turns at the top on their way to third, fourth and fifth.

Other final-hour improvements by the likes of Johann Zarco, Fabio di Giannantonio, Alex Marquez and Franco Morbidelli pushed Fabio Quartararo and Marc Marquez to eleventh and twelfth.

Quartararo had three Yamahas in the Monster pits while Marquez had four RCVs in the Repsol Honda garage (one with a new 'ground effect' style fairing).

While the other KTMs looked to start on 2022 spec, Jack Miller appeared to go straight to the new parts, including the carbon-black fairing tested by Dani Pedrosa at the Shakedown. Brad Binder switched to the new aero later in the day.

Miller was the top RC16 rider in 16th.

Following the Shakedown earlier this week, which saw Ducati's Michele Pirro fastest from Yamaha’s Cal Crutchlow, the 2023 MotoGP race riders take over at the Malaysian circuit from Friday to Sunday.

Rookie Augusto Fernandez is the only rider from this year’s 22-strong line-up eligible for both the Shakedown and Official test.

With Yamaha eying a significant improvement in top speed this year, much attention will also be on the max km/h of the M1s.

The Shakedown signs were promising, with Crutchlow recording a 335.4km/h. That was 5.2km/h faster than Fabio Quartararo managed during last October’s Malaysian Grand Prix qualifying and race (330.2). The Frenchman had clocked a 332.3 in FP3 with the aid of a slipstream.

Crutchlow didn't ride on Friday, but is expected back on track for days two and three of the Official test. Pedrosa is not due to ride at the Official test.

Testing took place from 10am to 6pm…

2023 Official Sepang MotoGP Test - Day 1 (FINAL)
1^10Marco BezzecchiITAMooney VR46 Ducati (GP22)1m 58.47s54/55335.4
2^2Maverick ViñalesSPAAprilia Racing (RS-GP 23)+0.130s65/67333.3
3˅2Enea BastianiniITADucati Lenovo (GP23)+0.262s42/54336.4
4˅2Jorge MartinSPAPramac Ducati (GP23)+0.267s21/67335.4
5˅2Francesco BagnaiaITADucati Lenovo (GP23)+0.387s23/58334.3
6˅1Aleix EspargaroSPAAprilia Racing (RS-GP 23)+0.471s44/49332.3
7^2Johann ZarcoFRAPramac Ducati (GP22)+0.496s46/56333.3
8^7Fabio Di GiannantonioITAGresini Ducati (GP22)+0.551s45/47332.3
9^1Alex MarquezSPAGresini Ducati (GP22)+0.566s47/53332.3
10^9Franco MorbidelliITAMonster Yamaha (YZR-M1)+0.648s54/59333.3
11˅5Fabio QuartararoFRAMonster Yamaha (YZR-M1)+0.952s47/58334.3
12˅5Marc MarquezSPARepsol Honda (RC213V)+0.954s23/58333.3
13˅5Luca MariniITAMooney VR46 Ducati (GP22)+0.999s21/50334.3
14˅2Miguel OliveiraPORRNF Aprilia (RS-GP 22)+1.260s39/50331.2
15^6Raul FernandezSPARNF Aprilia (RS-GP 22)+1.343s52/54331.2
16^4Jack MillerAUSRed Bull KTM (RC16)+1.356s48/53330.2
17˅4Joan MirSPARepsol Honda (RC213V)+1.362s47/53330.2
18˅4Alex RinsSPALCR Honda (RC213V)+1.493s49/66331.2
19˅3Augusto FernandezSPATech3 GASGAS (RC16)*+1.557s23/58326.2
20˅3Pol EspargaroSPATech3 GASGAS (RC16)+1.608s40/58331.2
21˅3Brad BinderRSARed Bull KTM (RC16)+1.615s18/60330.2
22=Takaaki NakagamiJPNLCR Honda (RC213V)+2.734s27/49328.2
23=Katsuyuki NakasugaJPNYamaha Test Rider (YZR-M1)+2.769s45/58327.2
24=Stefan BradlGERHonda Test Rider (RC213V)+5.031s2/3325.3

* Rookie

^X Rider is X positions higher than previous hour.
= Rider is same position as previous hour.
˅X Rider is X positions lower than previous hour.

2023 Sepang MotoGP Shakedown Test:
Michele Pirro ITA Ducati Test Rider 1m 59.803s
Official Sepang MotoGP records:
Best lap:
Jorge Martin SPA Ducati 1m 57.790s (2022)
Fastest race lap:
Jorge Martin SPA Ducati 1m 59.634s (2022)