Valentino Rossi admits he feels like he is in "big, big trouble" on his Yamaha MotoGP bike in the Argentinian Grand Prix, after finishing Friday practice well down the order.
Rossi has struggled with the 2017 M1 on corner entry, which has been exacerbated by new team-mate Maverick Vinales topping each pre-season test and then winning the season opener in Qatar.
While 38-year-old Rossi regrouped to finish third and join Vinales on the podium in Qatar, he spoke in Argentina about wanting to try a Michelin front tyre with the stiffer, end-of-2016 carcass, that he felt could help his problems.
Those tyres have been delayed by a transport strike in Argentina and are due to arrive at the circuit on Friday evening, but Rossi now feels he has bigger issues after finishing the first two practice sessions in 16th place.
"I was very happy to try [the stiffer tyre], but unfortunately today we don't have them," he said.
"Maybe we can have them tomorrow morning, but unfortunately the [current] rubber is too soft.
"It would be interesting to try, but we are in big, big trouble, so maybe we will not have time.
"Unfortunately I don't have this [feeling on corner] entry, I am not fast enough, I don't have enough feeling and I lose time every corner.
"In Qatar, we were able to improve. We need to improve and we will try tomorrow."
Rossi believes changes to Michelin's front tyre for its second season back in MotoGP are a factor, but he accepts that he is also finding it difficult to adapt to Yamaha's new bike.
"I have always a lot of movement in the front, but especially I am not able to enter [corners] fast," he said.
"I don't know how much is the tyre, but from me it's more from the bike.
"The bike is very different compared to last year, compared to the last Yamaha bikes.
"We tried a lot of things, but essentially I have the same problem as in Qatar [practice].
"Last year was a lot more natural. But you see Vinales is fast, always in front, so in the end the bike is good.
"We have to try to understand."