Yamaha rider Jorge Lorenzo believes he can mount a stronger MotoGP title challenge this season.
But Lorenzo said: "I think we are closer to Casey than last year.
"In testing we have been fast but we must wait and see. There are five or six riders who can fight for the title this year."
Lorenzo, 24, feared he may struggle to adapt to the new, larger, 1,000cc bikes for this season after damaging his left hand in a crash at the end of last season.
But, despite voicing fears over the new bike's top speeds, the Spaniard is happy with how he has settled on the new machine.
"I spent four months not riding the bike but it has been easier than I expected to come back," he said.
"On both runs of testing I have been close to the best lap times, so I am in a good position.
"The 1,000cc has more power, more acceleration, so you need more energy to control the bike. The weight is higher. But it is easier to ride because we have more torque and it doesn't move so much."
Lorenzo is out of contract with Yamaha at the end of the 2012 season, but has again expressed his desire to stay with the team for the rest of his career and add to his 17 MotoGP wins.
"Of course," he said. "When I first came to Yamaha in 2008 I immediately felt like I was in a family.
"We had the perfect bike from 2008-2010, and last year was difficult but in general we have a very good package.
"So my first option is Yamaha, I would like to finish my career here. If my bike is good here I don't see any motive to change."
The next round of pre-season testing takes place at Jerez in Spain this weekend, with the first race of the season in Qatar on 8 April.