Marc Marquez admits Honda must "improve a lot" to catch MotoGP rival Yamaha after world champion Jorge Lorenzo dominated the opening day of 2016 testing.
Lorenzo topped the times at Sepang by over a second ahead of teammate Valentino Rossi, with Marquez finishing down in seventh position, over 1.5 seconds off the reigning world champion's pace.
Marquez said Honda has not yet found the best settings for the new standard electronic control unit (ECU), which is mandatory for this year.
"Maybe Jorge is too far from what we expected," Marquez told reporters at the end of the day. "Valentino is closer, but we expected a little bit to need time with the electronics and to find the feeling with the tyres.
"With the tyres I basically didn't have a big problems, but it looks like with the electronics and with the characteristics of the engine I didn't feel comfortable, so for that reason today was a bit a special day.
"We are trying to work and trying to push, but it looks like we must improve a lot.
"We have to keep working to try to find better acceleration, which is where we lose more," added the Spaniard.
Marquez also admitted he was still adapting to the new Michelin tyres, which have forced the two-time champion to change his riding style, especially under braking.
"Maybe this is not the best circuit for my riding style, but with the Bridgestone I was able to brake really late and find the laptime there," Marquez added.
"But with the Michelin I have to change the riding style a bit and today I was braking late but not like with the Bridgestone.
"I tried to be safe. I'm still trying to learn how to ride with the Michelin. It looks like you also have to change the balance of the bike and at the moment I was riding like in the last race here in Malaysia."