Since winningꦬ on its MotoGP debut in Qatar, Ducati's GP18 has come under threat from the previous 2017 model in Argentina and Austin.

Pramac's Jack Miller was the🐼 top Ducati rider in Argentina, when Avintia's Tito Rabat finished right on the rear wheel of factory star Andrea Dovizioso.

While the Iไtalian then restored order with a fifth place in Austin, Miller and Rabat again beat the other GP18s of💯 Jorge Lorenzo and Danilo Petrucci.

At Jerez on Thursday, Miller's GP18 team-mate Petrucci was asked to explain the 🐽situation.

Whilst ruling out 🅷a repeat of the back-to-back comparison with the GP17 conducted by Lorenzo at the Thai༒land test, the Italian confirmed that the last two races have created some doubt.

"Maybe Jorge at that time was not so sure about his bike but for me in Sepang, Thailand and Qatar the GP18 was bett๊er," Petrucci said. "Now in the𝔍 last two races for sure we have this doubt at the moment."

Casti♍ng 📖his mind back to the start of pre-season testing, Petrucci added:

"After the first tes♑t in Sepang we said 'okay [the GP18 and GP17] are very similar'. Maybe with the GP17 you have to ride for two or three laps to make a good lap time. During testing with the GP18 on the first or second lap you already found the right feeling.

"Then in Argentina we started to hav🐼e some problems and we found the GP1ꩵ7 more competitive.

"Both Miller and Rabat were competitive in Argentina, maybe more than me and Dovizioso. For sure Jack did a great weekend in Argentina but even Tito w💃as pushing🌳 Dovi until the last corner.

"For me Austin was a disaster race but we saw that with the GP18 we change a lot of things, we struggled to find the good set-up. With the GP17 they know the set-up and they know pretty ൲well 💃the bike, because it's the bike from last year with all the data.

"Like every year, with a new bike at the beginning of the season you need to improve, to develop. Hopefully things can change here but I don’t know sincerely. We'll see. I hope🌃 the bike makes a small💮 step at this race."

Petrucci has more knowledge of the new🐽 Jerez asphalt than most having taken part in private test🍎s at the track in both November and March.

"In November the situation was better, like always in November we don't know why but since many years November is the fastest month at Jerez where we can set the record. I remember Loren🔜zo was very fast i🦩n November.

"But I tested here after Qatar and the situation wasꦆ a little bit worse. Especially in Turn 1 and Turn 8 the [new] asphalt is not so perfect. I mean there are many patches. I don't know why because in the other parts of the track the asphalt is very good. Lot of traction. And for sure is 100% better compared to the old asphalt. But in Turn 1 and 8 you have to be quite careful.

"Anyway, this extra grip is only better ꦇfor us. We struggle a lot when the compound of the tyre is harder, for example in Austin and A🍨rgentina.

"Here during the test we changed the bike a lot and I think we will start with the winglets from the first session tomorrow. So I think ♉[doing the tests means] I have an advantꦚage compared to the other Ducati riders.

"🐲Anyway I෴'m not happy about the result in Austin so I want to improve. In Argentina I was quite fast during the race but I started in 18th. I did a great comeback to 8th but it was not a great race.

"In Austin I fought very hard on Saturday to stay in the top ten, but then in the race I struggle﷽d a lot with the hard tyre and I was absolutely not competitive.

"I crossed the finish lineও at the end of🍨 the first lap in 17th but I was not able to be fast all the race. I don't know why. I maybe have some ideas."

From what he's seen at the priv🏅ate tests, the Repsol♐ Hondas will start as the team to beat this weekend.

"For sure here in Jerez I don't think we have the same💟 speed like in Tha💙iland and Qatar.

"I mean, we've been testing here for two days with Marquez and Pedr💞osa and they ꦦwere quite fast. Faster than us! So we have to work. For sure Honda made a big step ahead and we'll see.

"I lost many points in Austin. After Qatar I was fighting for a ♍top five in the championship and now I'm tenth, so I want to improve on my performance last year. I have more points than last year but every year it's a different story.

"But I'm quite fo🥃cussed and I want to use this extra test here to may🔴be start a step ahead."