After concluding the 2020 MotoGP season with eighth place at Portimao on Sunday, Aleix Espargaro will head to Jerez tomorrow for his debut on the 2021 Aprilia.

The team's private test had been due to start on Tuesday, but with poor weather forecast for Wednesday, Bradley Smith will give the new bikes a shakedown on Monday morning before Espargaro arrives at lunchtime.

"This season has been very tough, the last few weeks have been very tough. Here on Friday we did 2.5 hours of track time. So I'm very tired. But even like this all the team is very motivated," Espargaro said on Sunday evening.

"We have the new bikes in Jerez. It looks like on Wednesday it's going to rain so to anticipate we are packing everything and we're going to ride tomorrow already. So this is just to prove that we are very motivated and we think that next year is very important for us.

"There quite a lot of updates for the RS-GP 21 so I can't wait to try the bike. There is a different engine, different chassis, different swingarm. We will have more updates later in Malaysia. So there are many things to try. Different configurations."

Despite great expectations for the all-new 2020 machine, Espargaro finished just 17th in the world championship. His eighth place at Portimao was also the bike's best result of the season, meaning it didn't beat the sixth place by its predecessors.

"Next year is crucial for Aprilia and myself. If we cannot fight for the top six every single race, it will not be not a good year at all," Espargaro said.

The Spaniard was expected to be joined by his 2021 team-mate for the test, with American Moto2 rider Joe Roberts moving into a surprise pole position on Friday at Portimao.

But Espargaro confirmed team boss Massimo Rivola intended to announce Aprilia's new signing before the end of the race weekend, and the silence suggests the Roberts deal has hit the rocks.

It is rumoured that Roberts has now decided to stick with his original plan to join the world championship-winning Italtrans squad in Moto2 next year, which would put Aprilia back to square one in their rider search.

"No idea, sincerely!" Espargaro said of his future team-mate.

"I know it has been two very strange days for Massimo. I know very well that Massimo really wanted to announce yesterday or today the rider. If the announcement didn’t come it's because it's very difficult for him.

"The only thing I know is that tomorrow Bradley will be the first guy to shakedown the RS-GP 2021.

"This morning I texted Bradley and said 'mate, take care of my 2021 bikes tomorrow morning when you do the shakedown. I will arrive at lunchtime'.

"I'm fully committed with the team. It doesn't matter who is my team-mate. Aprilia needs me more than ever, so I'll try to rest a little bit today and then tomorrow go full gas for the 2021 season."

Smith raced in the opening eleven rounds of this season in place of the suspended Andrea Iannone (best result of 12th) before handing over to fellow test rider Lorenzo Savadori (best of 18th) for the final three rounds.

Espargaro said he doesn't know Smith's Aprilia future beyond the Jerez test.

Aprilia is now the only manufacturer still with technical concessions, which allows their race riders to take part in private tests. The other MotoGP race riders won't be on track again until Sepang in February.