Jorge Lorenzo conceded he was further behind the Repsol Honda of Marc Marquez than he would have wished as the factory Yamaha team prepared to wrap up testing early at the Circuit of Americas in Austin, Texas.
While Honda - which originally planned he private test - will participate in all three days, Lorenzo and team-mate Valentino Rossi will skip the final day on Thursday after obtaining 'all the data required'.
At 3pm local time on Wednesday, Lorenzo was third fastest on the time sheets with a best lap of 2m 04.664s after 17 laps.
MotoGP rookie Marquez held the top spot at that point with a time of 2m 04.363s from LCR Honda's Stefan Bradl (2m 04.640s), with Lorenzo next ahead of Dani Pedrosa on the second Repsol Honda RC213V (2m 04.686s).
Lorenzo said: “I feel better today, especially in the last run before the lunch-break. We changed the set up of the bike and we improved some tenths so we are closer to the fastest riders, but not as much as we would like.
“We were too soft in the suspension to start with, we made it harder and in this track it works,” added the current world champion.
“These two days that we are here I think is enough to get a good idea of set up and riding style. The fans will like MotoGP here, it is going to be a great show.”
Lorenzo is unhappy with the lack of rear grip from his YZR-M1, which is restricting his lean angle on the factory machine.
“We have been trying different set ups of the bike, no new parts, just playing with the set up, changing the suspension and forks and in the last run I improved half a second with set up changes,” he said.
“We still don't have enough grip on the rear so we can't lean over with confidence which is why we are further behind than in Sepang.
“I am adapting my riding style every lap a little for the track. In the main straight we are at 340kmh/h (211mph) which is an amazing speed; when you have to brake and put your helmet up the wind is very strong so it's difficult to be stable.”
Lorenzo and Rossi's next outing will be the final official MotoGP test at Jerez later this month.
Lorenzo improved his lap time but remained third fastest by the close of testing, 0.498s behind Marquez.