Jorge Lorenzo says there is more to come after setting the pace in opening practice for the US MotoGP at Laguna Sega.
The Yamaha rider ended the day 0.141s faster than Honda's Dani Pedrosa and 0.175s quicker than his world championship rival Casey Stoner, having been consistently on top of the times for much of the day.
"Today went pretty well, the bike felt okay," said Lorenzo. "P1 I'm happy with but we need to try to improve corner entry for the bike because there are some tenths in that and it will give me more confidence turning in.
"It's not so bad to begin and we will try to go faster tomorrow!"
Lorenzo told the official MotoGP website that he was pleased to be on a similar pace to the Hondas, but added that as the track rubbered in he could see them edging closer to him.
"Here especially the rear tyre grips a lot so it is difficult to improve the lap time you made at the beginning, but in general I am very happy because we are at least with them you know," he said.
"The soft tyre is much softer than last year but in the race it is impossible to use because only after three or four laps the tyre is finished. So we have to concentrate our work on making the hard tyre consistent and have a good pace and I think we have made it that.
"It will be tough [in the race]. Casey and Dani are trying so hard to be quick that the lap times are very close all the time. It will be a very difficult race on Sunday."
Lorenzo's team-mate Ben Spies was fifth fastest behind the world champion and the three factory Hondas.
"Today hasn't been bad, we've worked on a lot of different set ups," said the Texan. "We haven't found a perfect one, we've found a compromise so far but tomorrow we have a pretty good game plan on what we're going to fine tune from the bike we ended on today to get a bit of a better set up for front feel.
"I'm feeling good, I can tell the bike has it in it, you can see that from Jorge we're just not getting the maximum from it yet."