The 5.382s margin to victory for Aleix Espargaro in Doha was the closest an Aprilia RS-GP has ever been to the top of MotoGP.

It beat the previous best of 5.934s set by the Spaniard on his way to seventh place a week earlier, but on Sunday it was only good enough for tenth position.

Espargaro ran as high as third in the early stages and remained in contention for the RS-GP's first top five result until he was shuffled backwards in the closing laps.

The reason? Top speed, according to Espargaro, who peaked at 343.9km/h during the race compared with 356.4km/h (Jack Miller, Ducati) and 350.6km/h (Brad Binder, KTM) for the riders finishing just ahead of him.

"It is been a frustrating race. I think I did a good job, everything I could, but as I think everybody saw on TV, I lost a lot of ground on the straight," Espargaro said.

"The bike works super good, the tyres also, but on the straight it's very difficult because every lap from mid-race I lost one position.

"I tried to be aggressive, I overtook Zarco a couple of times and also Fabio but then on the straight, again I lose the position. So very difficult.

"Then in the last part of the race when the factory Ducatis started to drop, I felt I had more tyre than them, but there was no way to overtake. So, I think sincerely today we deserved a lot more than 10th place."

Espargaro had suffered on a full fuel tank in the season-opener, but felt much more confident in round two.

"I felt very good with the tyres. I think we took a lot more care than last race. I only slid in the last 2 laps. But with the front I felt a lot better than last week. We changed the bike a improve with a full tank and at the beginning of the race I was very strong," he said.

"But in the second part of the race the problem was the riders in front of me, especially the factory Ducati boys, start to lose ground but it was impossible for me to overtake them."

Nonetheless, with MotoGP now moving to tighter European circuits such as Portimao and Jerez, Espargaro is "fully confident" of taking the RS-GP into the top six.

"With the acceleration of the bike, the step we made from last season is unbelievable," he said. "I think we are in a very similar level from our competitors, but on the straight, especially in 5th and 6th gear, we lose close to 20ks so it's very difficult in a track like this to fight.

"But I think in Portimao and Jerez we can do very good races and fight for the top 6. I'm disappointed because I think we lost opportunities here in Qatar but anyway, we are eighth in the championship and not far so I can't wait for Portimao and Jerez.

"I wish it was next week because I can't wait to ride this promising bike in another track. I think in tracks with the long straights we need still need to work on the engine. But where the circuits are not that big, I think this year will be fun and we can challenge the top guys."

Aprilia's impressive Qatar form has only increased speculation surrounding Andrea Dovizioso's test for the team at Jerez in mid-April. While Espargaro has barely hidden his excitement at the prospect of Dovizioso contributing to the project, he made clear it wouldn't change his own input.

"I'm a rider who is fully motivated always so I don't need anybody next to me to motivate me. I'm able to motivate myself," he said. "And I think that what I say to the engineers is enough to improve the bike. Actually with my comments from last year I think we did with the engineers and everybody together in Noale a very good job with the new bike.

"They know what I'm missing, but to fight for the podium not to be in the top 10. So they know perfectly and they are working in Noale and we're hoping to receive new stuff around the Mugello race.

"So, I don't think a strong team mate will change anything on this side."

Espargaro current rookie team-mate Lorenzo Savadori, also still recovering from a shoulder injury, finished both Qatar races in last place.