Jorge Lorenzo concedes he could have "thrown in the towel" after a frustrating two-year spell at Ducati, but the three-time MotoGP champion feels rejuvenated and once again ready to challenge the supremacy of title-holder Marc Marquez - his new Honda stablemate.
Marquez has taken the sport by storm since his 2013 debut in the top category, winning the championship in five of the past six seasons, with fellow Spaniard Lorenzo standing between him and perfection having captured the 2015 title.
Yet injury clouds hover over both ahead of this weekend's season-opener in Qatar. Marquez has rated his fitness at "almost 100 percent" following a gruelling rehabilitation from December shoulder surgery, while Lorenzo missed the first pre-season test at Sepang after fracturing his wrist in a dirt bike crash.
Marquez has won just once among the elite at the Losail circuit in Doha, a venue where Lorenzo has triumphed on six occasions across three categories - including a hat-trick of MotoGP victories.
"This winter has been different due to the surgery, I worked hard with five hours of physio per day with only one goal: start in the best conditions in the first race of the year," the 26-year-old Marquez said.
"At the Qatar test I felt much better than at the Malaysia test and now I can say that I start at almost 100 percent."
"Honda have done a lot to improve the bike and in the test we were feeling strong, especially for a circuit which usually isn’t the best for us," he added.
After a fruitless 2017 campaign, Lorenzo rebounded with three wins a year ago - in Italy, Catalonia and Austria - before injury wrecked the latter part of his season.
He finished a career-worst ninth after missing four races having hurt his wrist following a nasty crash ahead of October's Thailand Grand Prix.
"Last year, honestly, was tough and I went through a period of emotional instability. I could have thrown in the towel, but that's not who I am," Lorenzo wrote on the official MotoGP website.
"Signing with Honda has been a massive injection of motivation. I'm convinced that, through my mentality, ambition and sacrifice, I can be very competitive. Fighting with Marc is a challenge for any rider and, at this point in my career, it's a great boost.
"So far, I'm the only rider who has managed to win a title against Marc. Nothing is impossible and with effort, I want to prove it again."
Italy's Andrea Dovizioso, who finished second to Marquez, is confident of launching of a more consistent title bid and will be joined by compatriot Danilo Petrucci at Ducati this term.
"2018 was a very positive year for me. We started with a victory and, even if we had some ups and downs, the difficulties pushed us to look in new directions and half-way through the season we made a big step forward," he said.
"The expectations are high, I have a great feeling with both the bike and my crew, and we can count on more experience."
Rossi enters 20th season
Valentino Rossi, who turned 40 last month, is coming off just a third winless season in 19 at the top level as he finished a distant third overall.
The seven-time premier class champion lagged behind factory Yamaha teammate Maverick Vinales during February's testing in Qatar, but team boss Massimo Meregalli is convinced the iconic Italian will shake off his early struggles.
"He hasn’t been that fast and hasn’t set very nice lap times, but I'm not worried because, considering our previous experiences, we know that on Sundays at race time he’s in front," Meregalli told Motorsport.com.
Four rookies will join the 22-man field for the new campaign, with reigning Moto2 champion Francesco Bagnaia making the step up alongside French teenager Fabio Quartararo.
Last year's Moto2 runner-up, Miguel Oliveira of Portugal, and Spanish 2017 Moto3 champion Joan Mir also make their premier class debut this weekend.