Sam Lowes and Danny Kent set fast lap times during their debut test with Kalex Moto2 machinery, at Jerez.
Alex Rins led the test with a best lap of 1m 42.333s, half-a-second under the pole time from this year's Spanish Grand Prix.
But former Speed Up star Lowes was just 0.099s slower in second place, with newly crowned Moto3 champion Kent a close fifth overall (+0.323s).
“I'm really impressed by the team and the bike!” said Lowes, whose move to Gresini includes an Aprilia MotoGP seat in 2017. “From the first moment I felt that the potential is very high and I'm satisfied with the work done in these two days, in which I did a lot of laps , a record for me!
“I tried many things on the bike, mostly to get acquainted to it and to understand how it reacts to set-up changes. It was a great start, the guys from the team are fantastic and I could not be happier.”
Team principal Fausto Gresini added: “Our priority was to familiarise Sam with the new 2016 Kalex Moto2 bike and with the Ohlins suspension, and I think he did it very well.”
Kent was completing his first Moto2 laps since 2013 at Tech 3, while his Kiefer run-Leopard team is returning to the class they won with Stefan Bradl in 2011.
"The first impression after my comeback to the Moto2 category has been very good,” Kent declared. “After a couple of laps I felt like back home in this class and it took not a long time to set faster lap times than in my Moto2 season in 2013. In the end I was 1.5 second faster than before at this track. So not only for this I've to say that the first feeling with the Kalex bike is really good.
“In general, it's a great bike to ride and the support from Kalex we already are receiving is really excellent. However, this was just our first two-day test for the upcoming season so there is still a lot to learn for everyone in the team but also for my side I must working hard to change back my riding style to Moto2 in order to get closer to the front guys.
“Before heading into the two-month winter break it was important to do this two-day test here in Jerez so I can go back home now to start my fitness training with some slightly changes do the programme to come back in 2016 well prepared for our first Moto2 campaign."
Kent's new team-mate Miguel Oliveira was 13th quickest, 1.5s from Rins.
Lowes will test at Valencia on November 16-17.