Yamaha duo Valentino Rossi and Maverick Vinales will look to rediscover their impressive early-season form at this weekend's French MotoGP after a difficult race in Spain.

Veteran Italian Rossi leads the championship with 62 points after four rounds, while Vinales is a close second after winning the first two races in Qatar and Argentina.

But the pair struggled in Jerez last time out, Vinales finishing sixth following his retirement at the Grand Prix of the Americas and Rossi trailing home in 10th as Dani Pedrosa and Marc Marquez sealed a one-two finish for Honda.

"After the difficulties during the Jerez weekend, the Le Mans GP will be very important," said Rossi, who finished on the podium in each of the opening three races before his Spanish travails.

"It is true that we are still first in the championship standings, and this is nice for us, but we need to improve the bike to be really competitive," added the 38-year-old, who is a three-time winner at Le Mans.

Vinales hopes the return to the site of his first MotoGP top-three finish a year ago, when he was still with Suzuki, can spark a quick recovery.

"The race in Jerez was very difficult for us," admitted the Spaniard. "Luckily during the test on Monday in Jerez we had a totally different result, it was a really good test.

"For that reason we're arriving in France with a positive mind. Le Mans is a good track for us, it suits my riding style, and we can do a really good job there."

Both Marquez and Pedrosa have both cranked up the pace after failing to finish in Argentina, but their thoughts were with former world champion Nicky Hayden on Wednesday after the American was seriously hurt while riding his bicycle in Italy.

He was rushed to hospital with severe chest and head injuries, according to local reports.

"Best wishes @NickyHayden! Stay strong my friend! #GoNicky," Pedrosa tweeted, while Marquez also took to Twitter to post a picture of himself alongside the 2006 MotoGP champion. "My thoughts are with you," he added.

Over 100 000 fans are expected to flock to Le Mans for the race weekend, with French rookie Johann Zarco set to garner plenty of attention after making a seamless step up from the Moto2 category.

"I have the chance to really impress the general public in MotoGP. That wasn't the case in Moto2 despite my two titles," said Zarco.