Jorge Lorenzo took a huge step toward regaining the MotoGP title as he won the San Marino Grand Prix in Misano and rival Dani Pedrosa crashed out.

Repsol Honda rider Pedrosa endured a torrid start and was then taken out by Hector Barbera halfway through lap one.

That left the way clear for Lorenzo to cruise to victory and extend his championship lead from 13 to 38 points.

Italy’s Valentino Rossi was second in his home race for Ducati while Briton Cal Crutchlow also crashed out.

On a weekend when MotoGP remembered the late Marco Simoncelli at the circuit now named after him, it was fitting that his close friend Rossi produced his best ever ride on the Ducati and Alvaro Bautista took third place on the Gresini Honda which was set to be ridden by Simoncelli this year.

Rossi told BBC Sport: “This second place is something special.

“I have a lot of fans in Misano, my hometown is only a few minutes away, but more importantly this is in the name of Marco.

“This result is for him and for his family. I think Marco helped me to achieve this today.”

Bautista said: “I am very emotional to get my first podium. I do this in memory of Marco - I dedicate the race to him.”

The result was a dream scenario for some, but a nightmare for Pedrosa who saw his title hopes suffer a massive blow in a chaotic few minutes.

The Spaniard had qualified in pole position but the original start was aborted when Karel Abraham stalled his Ducati on the grid.

That led to a delay of five minutes or so, during which Pedrosa had a problem with the front wheel of his bike.

He was forced to start the race from the back of the grid, and although he made up several places in the first few corners, he was then launched off his bike when Barbera ran into the back of him.

Barbera - who has had a season littered with crashes that have seen him break a leg and injure his back - went into the turn too quickly and could not stop, clattering into Pedrosa and sending him off into the gravel.

Lorenzo was left with an untroubled run to his sixth win of the season, and a result that almost trebled his championship lead.

British rider Crutchlow made a poor start from third on the grid and had been shuffled back to fifth before he crashed out on lap three.

Northern Irishman Jonathan Rea, making his MotoGP debut in place of injured world champion Casey Stoner, had a solid race to finish eighth.

Dani Pedrosa says his chances of winning the MotoGP title “are not over” despite falling 38 points behind leader Jorge Lorenzo.

Pedrosa was due to start the San Marino Grand Prix from pole position but had a problem with his bike on the grid.

He eventually started from last place but crashed out on the opening lap when he was hit by Hector Barbera.

He said: “Now the championship is obviously more uphill for me, but I will continue. It’s not over for me.”

The original start was aborted when Karel Abraham stalled his Ducati on the grid.

That led to a delay, during which Pedrosa had a problem with the front wheel of his bike and was forced to start from last place.

“It was total chaos at the start. It all began with the restart because the procedure was not at all clear,” he said.

“Nobody knew if it was one minute until the start, three minutes - we were also getting different information about the number of laps we would race, 26 or 27.

“Then suddenly we were told it was one minute to the start of the race, with no board signage, nothing.

“The mechanics were rushing to prepare and when they tried to take off the tyre warmers my front wheel was somehow locked.

“They tried to unlock it but they weren’t able to and they put me to the back of the grid.

“I tried to remain focused, not make any mistakes on the first lap, make clear moves to overtake riders and I was eighth or ninth by the sixth corner when Barbera hit me from behind, and that was it.”

Barbera - who has had a season littered with crashes that have seen him break a leg and injure his back - did apologise to his compatriot.

He said: “I took out Dani and that was the last thing that I wanted to happen.

“It was my fault that he crashed out and I apologise profusely to him for that.”

Lorenzo was left with an untroubled run to his sixth win of the season, and a result that almost trebled his championship lead.

“I’m very upset because even though it’s easy to say now, I think I could have had a chance to win this race, even starting from the last place on the grid,” Pedrosa added.

There are five races left in this season’s championship, with the next race at Aragon in Spain on 30 September.

Results and standings after 13 of 18 races

Yesterday’s results

1. Jorge Lorenzo, Yamaha, 42:49.836

2. Valentino Rossi, Ducati, +4.398

3. Alvaro Bautista, Honda, +6.055

4. Andrea Dovizioso, Yamaha, +6.058

5. Ben Spies, Yamaha, +7.543

6. Stefan Bradl, Honda, +13.272

7. Nicky Hayden, Ducati, +40.907

8. Jonathan Rea, Honda, +43.162

9. Randy De Puniet, ART, +1:09.627

10. Michele Pirro, FTR, +1:13.605

Drivers’ championship

1. Jorge Lorenzo, Yamaha 270

2. Dani Pedrosa, Honda 232

3. Casey Stoner, Honda 186

4. Andrea Dovizioso, Yamaha 163

5. Cal Crutchlow, Yamaha 122

6. Valentino Rossi, Ducati 120

7. Alvaro Bautista, Honda 118

8. Stefan Bradl, Honda 115

9. Nicky Hayden, Ducati 93

10. Ben Spies, Yamaha 77