On only his 15th lap with the 1000cc Yamaha, Ben Spies set a lap time good enough to finish Monday's Brno test third fastest, just 0.138sec behind the 2012 Honda of Casey Stoner.
With Spies' team-mate Jorge Lorenzo sandwiched between the pair, it was a highly impressive debut for the 2012 M1, especially since Stoner had already completed two days of private testing on the Honda RC213V.
Spies, a US and World Champion on 1000cc Superbike machinery, was still nursing the pinched nerve he had struggled with all weekend, but was able to try the latest 800cc developments (15 laps) before leaving the test at lunchtime.
"The 800cc upgrades we tested this morning were positive, hopefully there's more in that direction in the future as well," said the Texan of the engine and electronic upgrades.
"With the 1000cc bike it was a pretty successful first day. We didn't change much on it, pretty much just rolled out and did some laps to get as much data as possible.
"We made some small changes to see how differently it affected the bike compared to the 800. There's more improvements to be made for sure but for the first day to go faster than the 800 was a surprise.
"My arm is feeling better and better, I'm getting a check up when I fly home to the US on Wednesday but should be fit and ready for Indianapolis.”
Spies' best lap on the 1000cc M1 was 0.878sec faster than his best lap on the 800.