Jack Miller believes that Aprilia Racing is a genuine threat for victory in this weekend’s Catalan MotoGP after it finished one-two in Friday practice.

Maverick Viñales was second-quickest in both of the first two, 45-minute sessions at the Circuit de Barcelona-Catalunya, with Aleix Espargaro topping Free Practice 2 with a 1:39.402s.

That put Aprilia’s ‘captain’ 0.303s up on team-mate Viñales and almost half a second clear of the rest of the field, with Gresini Racing’s Enea Bastianini best of the rest courtesy of a 1:39.890s on his GP21-spec Ducati Desmosedici.

Miller was seventh-quickest, three spots behind fellow Ducati Lenovo Team rider Francesco Bagnaia, having gone as quick as a 1:40.095s.

The Queenslander was one of several who think that the Noale marque’s practice pace was no fluke, drawing comparisons between the Catalunya surface and that of Argentina’s Termas de Rio Hondo, where Espargaro broke through for his and Aprilia’s first premier class race win in April.

“I feel okay; the bike’s working pretty well,” he told MotoGP’s official website.

“For sure, the grip level out there at the moment is not fantastic by any stretch of the imagination. Always, the grip’s pretty low here in Barcelona but, year-by-year, it’s getting worse and worse.

“And again, like in Argentina, the Aprilias… when the grip levels are quite low, they both seem to be very strong.

“We have a big weekend ahead of us; we need to keep working.

“The pace wasn’t the greatest in the FP2 – I wasn’t satisfied with that – so we’ll try to work on that on Saturday and of course qualifying’s going to be really important, so we need to work on that quite a lot.”

Bagnaia was even stronger in his language, describing himself as “shocked” by Aprilia’s speed.

“I was shocked at the start,” said the Italian, who followed one of the RS-GPs in Free Practice 1.

“But it was the first laps, and they already rode this year in this track with the street bike.

“So, it’s a little advantage but for sure Aprilia in a situation of low grip is very competitive.

“In traction, they [Aprilia] have really good traction. It’s something I already seen all year.

Fabio Quartararo, who is eight points clear of Espargaro at the top of the championship, was surprised at just how far ahead the Aprilias were.

“We know from Argentina that with low grip, the Aprilias go super-fast,” said Monster Energy Yamaha rider.

“But even on race pace, today I was six to seven tenths slower than Aleix.”

Fellow Yamaha pilot Andrea Dovizioso was briefly a test rider for Aprilia last year, after a long stint at Ducati, and offered his insight into the situation.

“The only thing I can see is the grip they have,” remarked the WithU RNF rider.

“On the rear, it’s really good. For sure, it’s mechanical grip; at the level we’re at now with the electronics, the difference is just mechanical.

“When I tried the [Aprilia] bike, straight away I felt similar to the Ducati, that the grip is very good.

“I don’t know what they changed from the bike I tried last year. In Argentina, the grip was very low and they were so good.

“For sure, I’m not the fastest in the middle of the corner, but Aleix overtook me around the outside at Turn 3… So I was a bit surprised!”

Free Practice 3 at Catalunya starts at 17:55 AEST, before Free Practice 4 at 21:30, Qualifying 1 at 22:10, and Qualifying 2 at 22:35.