Spaniard Jorge Lorenzo clinched his first MotoGP win after a thrilling duel with compatriot Dani Pedrosa at the MotoGP of Portugal at the Estoril circuit on Sunday.

Seven times world champion Valentino Rossi was third in the 28-lap, 117.096-km race.

Lorenzo, on a Yamaha, clocked 45 minutes 53.089 seconds, 1.817 seconds faster than Pedrosa, on a Honda.

The trio had a fearsome battle over the opening laps before Lorenzo passed the other two in rapid succession on the 13th.

Lorenzo and Pedrosa share the lead in the world championship standings after three races, with both on 61 points. Yamaha's Rossi is third with 47 points.

"It's fantastic and unbelievable [the victory], a feeling that cannot be described," said the 20-year-old Lorenzo, who started on pole.

Lorenzo said he felt some pain in his arms during the race but that did not stop him from keeping up the pace, especially after the rain stopped.

"Rain is always something scary for a rider but when the track became dry I had a perfect rhythm. I managed to overtake Dani Pedrosa and after that things went pretty well," he said.