ALCANIZ, Spain -- Jorge Lorenzo won his first race of the MotoGP season at the Aragon Grand Prix on Sunday after points leader Marc Marquez and Honda teammate Dani Pedrosa both crashed in the rain.
Lorenzo changed for a bike with tires for wet conditions after it started to rain halfway through the race. The move proved the right one after Marquez and Pedrosa both decided to push on with tires for dry surfaces, only to fall with a few laps to go.
Lorenzo's teammate Valentino Rossi also crashed before the rain started and was taken to a hospital for testing after being diagnosed with a concussion.
"With these conditions I was a little worried," said Lorenzo. "I knew that I could fall at any moment. But I started well, then I didn't feel as confident as Marc and Dani and said, `Oh well, I will try for third.' But I decided to go for it and went into boxes. It was a tough choice because it is always risky to change tires."
Lorenzo eased his Yamaha through the final three laps to finish in 44 minutes, 20.406 seconds. He was more than 10 seconds ahead Aleix Espargaro, who edged Cal Crutchlow for second place.
It was Lorenzo's first win since the two-time champion won the last race of 2013.
Just as Lorenzo pulled into pit lane to change bikes, Pedrosa fell with four laps to go. Marquez had one more chance to learn from his Honda partner's mistake, but he opted to ride on, only to fall a lap later.
Marquez finished 13th, one spot ahead of Pedrosa.
After having won 10 of the first 12 races, Marquez has crashed during the last two. He finished the previous San Marino GP in 15th after falling.
Marquez said that he didn't know that Pedrosa had fallen.
"If I had, I would have stopped," said Marquez. "I said that here at Aragon I would go for it, but I didn't have experience for these conditions and they got the better of me. There are four races left and I am close to the title."
Marquez leads the standings with 289 points. Pedrosa is next with 215, with Rossi another point behind.
Even before the rain provoked havoc, bikes were sliding off the 5-kilometer (3.15-miles) MotorLand Aragon circuit.
Rossi, who had won the previous San Marino GP, crashed on the third lap when trying to overtake Pedrosa on the outside. He was carried off on a stretcher.
According to the MotoGP website, Rossi sustained a concussion and "lost consciousness briefly after the crash but regained it quickly."
A lap earlier, fellow Italian Andrea Iannone had also crashed after jumping from third on the grid to take a brief lead of the race. He wiped out after losing a thrilling joust for first place with Marquez.
Andrea Dovizioso, another Italian, fell after he had changed to tires for rain.
Spaniards also won in the smaller classes.
In Moto2, Maverick Vinales won ahead of Esteve Rabat and Johann Zarco.
Rabat kept his lead in the points standings with 278. Mika Kallio has 245, followed by Vinales with 204.
In Moto3, Alex Marquez, the younger brother of Marc, moved into first place in the points standings after finishing an accident-filled race in second place behind winner Romano Fenati.
Danny Kent finished third.
Marquez overtook Australia's Jack Miller in the points standings after Miller fell when the two riders came into contact.
Marquez has 206 points, while Miller has 195.
The Moto2 and Moto3 races were delayed due to heavy morning fog that covered the track.