Valentino Rossi finished an incident-marred opening day of the Japanese MotoGP at Motegi in seventh place.
The Doctor was only 0.381s behind pace setting Movistar Yamaha team-mate Jorge Lorenzo, but that time was set after changing back to soft tyres at the end of the session.
"A mixed day, because this morning I was not so bad. I was quite fast and strong," began Rossi, fourth in FP1. "But this afternoon was a difficult practice. We tried the harder tyre, but both the front and rear doesn't give very good grip, so I lose some feeling.
"At the end we put back the softer tyres and I improved the lap time, but still was not enough, because I'm not very happy about the setting and the balance of the bike.
"This afternoon we tried to do something different. We modified quite a lot, but is not the right way. I'm not strong enough. I'm not so far but it's not the way.
"I'm not good, it's very difficult to stop in braking and so we have to work and try to recover."
Rossi also had a theory as to why the afternoon session saw so many falls, including big highsides for Dani Pedrosa and Eugene Laverty. Pedrosa has been diagnosed with a fractured collarbone, while Laverty has been sent to hospital for precautionary CT scans.
"About the tyres, the feeling is not so bad, also the lap time is not so far from last year. But this afternoon we have unfortunately a lot of crashes, and some injury for Pedrosa," Rossi said.
"It's also because in the afternoon it looked like the temperature dropped very quick and after became dangerous. So good luck to Pedrosa and, for us, tomorrow we will try to modify the balance and try to be stronger."
Rossi is 52 points behind runaway MotoGP title leader Marc Marquez, but 14 ahead of Lorenzo.
By Peter McLaren