PARIS, France - The wraps will come off the 2013 MotoGP season in Qatar this weekend with pre-season testing suggesting Jorge Lorenzo has a huge fight on his hands to defend his World championship title.The Spaniard prevailed in a gripping season-long tussle with Dani Pedrosa to claim the 2012 crown in the penultimate race in Australia after his Honda rival crashed out.Pedrosa, on the speedy and reliable Honda, will be hungry to go one better but Lorenzo faces an arguably greater danger much closer to home. Nine-times champion Valentino Rossi's decision to end his disastrous Ducati spell and return to Yamaha injects spice to the 2013 campaign given the two riders' stormy past.'DIFFERENT MOMENT'Rossi and Lorenzo "have history" from their previous spell as team mates - their relationship became so toxic at one stage that a wall was erected between their two garages to stop the sharing of data. Yamaha says they are now willing to let bygones be bygones - starting in Doha.Yamaha team manager Wilco Zeelenberg told BBC Sport: "They are in a completely different moment in their career. Three years earlier there was quite some tension but now they accept each other very well. Vale is still very fast and Jorge realises that he's a nine-times World champion, so he has to beat him."Before, Jorge was the upcoming young guy, but he's become a double MotoGP World champion. Valentino also accepts that Lorenzo is a fast rider and a World champion. That's a big difference compared to 2010."Rossi said durijng testing in Sepang earlier in 2013 that he would challenge for the title. "I can start the championship with the target to fight Lorenzo and Pedrosa," said the 34-year-old Italian, adding that he was inspired "a thousand times more than in the past two years".'BETTER TOGETHER'And, another sign of the new entente cordiale between the Yamaha partners, Rossi lavished praise on Lorenzo. "For me, I think he is perfect. He is very fast in all conditions. He is very fast from the beginning. He never makes mistakes and has a high level of concentration. He is at the top."Lorenzo, extolling the virtues of unity over divisiveness when quizzed on Rossi's return, said: "It's better to work together than to go separately. We are in the same team."Would their relationship be better second time around? "Yes, probably something has changed. I hope so. I think he hopes so. You can share information. You can speak about improvements. We must pass some notes - together is better."Pedrosa, regarded as favourite for the title by many after running so close in 2012, will be partnered at Honda by 20-year-old Marc Marquez, the 2012 Moto2 champion, as replacement for Casey Stoner, the Australian former champion who has taken early retirement.