Valentino Rossi fears he will not be able to sustain a strong race pace throughout Sunday's Spanish Grand Prix unless he can get to grips with this weekend's tire choice.
Rossi was third and fourth in the two Friday practice sessions at Jerez, as his Yamaha teammate Jorge Lorenzo led the way. Although happy with his position, Rossi was concerned about tire management.
"I'm more worried about the rhythm," he said. "I wasn't very confident with the hard rear tire in practice. I tried it but unfortunately the hard rear doesn't have enough grip on the very edge. I'm quite worried if I have to race with the soft because with this temperature it will become quite difficult to do the 27 laps."
Lorenzo was content with the soft tire, although he will try the hard in Saturday practice.
Yamaha had also set the pace at Jerez in pre-season testing, but Rossi believes Honda's Dani Pedrosa will be a serious threat in the race. Pedrosa was just 0.003 second behind Lorenzo in the morning.
"Maybe we have some advantage compared to the Honda in the colder conditions, like in the test," said Rossi. "But anyway Dani is very fast here.
"I think that for Sunday, Dani and Jorge are the riders with more of a chance to win."
The two works Yamahas of Lorenzo and Rossi, factory Honda pair Pedrosa and Marc Marquez, and Tech 3 Yamaha's Cal Crutchlow formed the top five in both sessions, several tenths clear of the rest of the pack.