DOHA, Qatar - MotoGP World champion Jorge Lorenzo started the 2013 season with the fastest lap as Yamaha swept the top three places in Thursday's (April 4) first free practice for the floodlit Qatar GP on Sunday (April 7, 2013).The Spaniard lapped the Losail desert circuit in 1min56.685 right at the end of the session.Britain's Cal Crutchlow on a non-works Tech3 Yamaha was second-fastest in 1min56.743 ahead of Lorenzo's Italian team mate Valentino Rossi (1min56.756).Double champion Lorenzo said: "It's a very good way to start the season. To have three Yamahas in the first three positions like in (the final test in) Jerez means this track can be positive for us."We need to improve, though, because the other guys will come in the next practice."Spanish MotoGP debutant Marc Marques, 2012's Moto2 champion, was fourth and the fastest Honda rider. Team mate, compatriot and title favourite Dani Pedrosa was eighth.