Italy MotoGP, Mugello
Date: Saturday 5 June/Sunday 6 June
Saturday BBC coverage: Qualifying - 1150-1500, BBC Red Button/online
Sunday BBC coverage: 125cc and Moto2 races - 0950-1205, BBC Red Button/online; Race live - 1230-1400, BBC Two/online; MotoGP Extra - 1400-1430, BBC Red Button/online
By Steve Parrish
BBC MotoGP commentator
Rivalry between team-mates Rossi (46) and Lorenzo (99) is fierce
Jorge Lorenzo took the plaudits for the second race in a row following his victory in France, but Casey Stoner's second consecutive crash was the big story coming out of Le Mans.
The 2007 world champion was my tip for the title this year, but the 24-year-old Australian has collected just 11 points from the first three races and lies 59 behind championship leader Lorenzo.
Stoner has not done a lot wrong so far, yet he must be a worried man. There is speculation the chassis on his Ducati is not working as it should but I don't think even he knows what the problem is.
He looked totally astonished after the race in France and there must be concern about the damage that is being done to his confidence.
It used to be the case that Stoner was the only rider who get the best out of the Ducati. But now team-mate Nicky Hayden is riding it better than ever while Stoner is the one struggling.
He would probably like last year's bike back if he could. But the six-engine rule means that could be hard. Ducati have probably got six 2010 engines sitting there waiting to be used.
I am sure Stoner will bounce back and win races, but the championship is already over for him this year. In my view, the title is a Yamaha shoot-out between Lorenzo and Valentino Rossi.
There are still hundreds of things which could happen, of course, but Yamaha seem to have the perfect motorbike at the moment.
Lorenzo has just managed his first back-to-back wins in MotoGP, coming out on top in both Jerez and Le Mans to lead Rossi by nine points in the standings.
It must be an odd sensation for Rossi to have a team-mate who is more consistent than him and I bet he wishes he could take down the dividing wall he had installed in the Yamaha garage.
The wall was designed to stop Lorenzo profiting from Rossi's information. Now the Italian might be the one wishing he could look at his rival's data.
If Lorenzo could make it three wins in a row in front of Rossi's home fans at Mugello this weekend, that would really grind the defending champion's gears.
Rossi's mechanic Jeremy Burgess says his man is still not 100% right after suffering a shoulder injury a few weeks ago and cannot set the bike up so well in practice.
This is another example of where Lorenzo has the upper hand. At 23, he still bounces when he falls. At 31, Rossi doesn't, which means injuries linger longer.
Lorenzo poses the biggest challenge to Rossi that he has faced in the last five years.
If the Spaniard beats his team-mate in front of those adoring Italian fans on Sunday, it would have so much significance to both men.
My Mugello MotoGP race prediction:
1) Valentino Rossi 2) Jorge Lorenzo 3) Casey Stoner
Steve Parrish was talking to BBC Sport's Julian Shea.