Casey Stoner is certain that Honda's current deficit to Yamaha in the MotoGP title battle can be traced to the revised front tyre that Bridgestone recently introduced.
Yamaha's Jorge Lorenzo has now won the last three grands prix, and pulled out a 25-point championship advantage over Stoner.
Honda has been troubled by a chatter problem all season, and Stoner reckons that the change of tyre exacerbated the issue.
"We made an improvement in Catalunya with the rear chatter. But we know we've got front chatter from Portugal and races previous," he said. "But now it's extreme with this new front tyre.
"I voiced this from the first moment we tested this tyre. We've developed the whole bike around the one before, and they've put one in one third of the way into the season and it's put us in a really difficult situation.
"We thought we'd be able to set things up around it, and we haven't been able to thus far. But we've got a long season."
Stoner doubts that Honda will be in any better shape in the next race at Assen.
Last year he finished second to Yamaha's Ben Spies in the Dutch TT while sore from a practice crash, but reckons he might have struggled to make it onto the podium there had Marco Simoncelli and Jorge Lorenzo not collided at the first corner.
"We've had some great races there and also some tough ones. It was a pretty big crash last year and I was pretty sore. We were lucky that Jorge and Marco weren't in that race because they had a higher pace than us and it would have made things difficult. In the end Ben was able to hold us off," said Stoner.
"Hopefully this year we can go there with a bit more pace and without an injury and see what we can do, but we've got to fix something with the bike first."