Jack Miller builds momentum by staying on top of the timesheets during final practice for the 2021 Americas MotoGP at a bumpy COTA.

World champion Joan Mir began FP4 with an engine failure but finished it in second place, 0.152s behind the Ducati rider, whose team-mate and title contender Francesco Bagnaia was third.

Mir's Suzuki spat out smoke and flames as he accelerated onto the back straight, with Miguel Oliveira forced to take avoiding action just behind.

Pol Espargaro then fell from his Repsol Honda, meaning he also missed vital track time, with brother Aleix Espargaro crashing at the fast Turn 2 at the end of the session.

While all riders selected the hard front tyre, there was a variety of rear compounds in use. Most riders opted for the medium rear but Johann Zarco was fastest for most of the session on a soft.

By contrast Miller (including his fastest lap), Marc MarquezAndrea Dovizioso, Valentino Rossi and Franco Morbidelli used part of the session to gather data on the hard rear. Bagnaia, Marquez, Nakagami, Oliveira and Aleix Espargaro finished the session on the soft rear.

Qualifying 1, for those outside the top ten after third free practice, including Mir, will now get underway.

Marc Marquez has a perfect pole record at the Texan track and has won six of the seven MotoGP races, falling while leading in 2019.

Johann Zarco is riding for the first time since arm pump surgery, while Mir has a Kevin Schwantz-style helmet and racing number this weekend.

MotoGP is returning to COTA for the first time since the 2019 event, after which further resurfacing work was carried out on around 40% of the track (Turns 1-2, 9-10, 16-19, plus the back straight) to alleviate bumps. However, bikes and riders are still being badly kicked around, especially through Turns 2 and 10.

As a result of the resurfacing and change of date from April, Michelin is providing a fourth rear tyre option (two hard compounds), while wet weather is also forecast.

COTA has the most corners (20) in MotoGP, including the slowest of the season at just 50km/h (Turn 11). The following back straight is the longest in MotoGP at 1.2km and ends with the hardest braking on the calendar, from over 330km/h to less than 60km/h.

Maverick Vinales has withdrawn from the COTA event after the tragic death of his young cousin Dean Berta Vinales in last weekend's Jerez WorldSSP300 race...

Austin MotoGP, COTA - Free Practice (4) Results
1Jack MillerAUSDucati Team (GP21)2'04.028s10/12347k
2Joan MirSPASuzuki Ecstar (GSX-RR)+0.152s5/8340k
3Francesco BagnaiaITADucati Team (GP21)+0.327s11/13347k
4Johann ZarcoFRAPramac Ducati (GP21)+0.347s3/12350k
5Fabio QuartararoFRAMonster Yamaha (YZR-M1)+0.351s5/12338k
6Takaaki NakagamiJPNLCR Honda (RC213V)+0.376s10/12343k
7Alex RinsSPASuzuki Ecstar (GSX-RR)+0.434s9/11340k
8Marc MarquezSPARepsol Honda (RC213V)+0.516s6/12342k
9Miguel OliveiraPORRed Bull KTM (RC16)+0.683s4/13341k
10Aleix EspargaroSPAAprilia Gresini (RS-GP)+0.683s5/10344k
11Luca MariniITASky VR46 Avintia Ducati (GP19)*+1.021s9/10338k
12Enea BastianiniITAAvintia Ducati (GP19)*+1.043s8/11347k
13Jorge MartinSPAPramac Ducati (GP21)*+1.187s9/12346k
14Brad BinderRSARed Bull KTM (RC16)+1.284s7/11344k
15Andrea DoviziosoITAPetronas Yamaha (YZR-M1)+1.321s10/11338k
16Alex MarquezSPALCR Honda (RC213V)+1.379s6/12345k
17Pol EspargaroSPARepsol Honda (RC213V)+1.401s5/10344k
18Valentino RossiITAPetronas Yamaha (YZR-M1)+1.523s10/13336k
19Iker LecuonaSPAKTM Tech3 (RC16)+1.538s4/9342k
20Franco MorbidelliITAMonster Yamaha (YZR-M1)+1.586s4/9335k
21Danilo PetrucciITAKTM Tech3 (RC16)+2.157s3/11341k

* Rookie

Official COTA MotoGP records:
Best lap:
Marc Marquez SPA Honda 2m 2.135s (2015)
Fastest race lap:
Marc Marquez SPA Honda 2m 3.375s (2014)

By Peter McLaren