Casey Stoner said traffic prevented him from showing his full potential in MotoGP qualifying at Laguna Seca, after losing pole position to Jorge Lorenzo by 0.074 seconds.
Lorenzo and Stoner exchanged provisional pole twice in a thrilling finale to the United States Grand Prix grid-deciding session. But Stoner encountered traffic on both his late runs, and ultimately saw his Yamaha rival secure the top spot - ending a run of Honda poles that began at Estoril in early May.
"It was more than disappointing, this session," said Stoner. "We made some pretty good progress with the hard tyre. When we went to the soft tyre, I never got one clean lap. There was always someone in the way, either cruising around or backing off in the middle of the corner.
"It's more than frustrating, to be honest. We knew our potential was higher than that and we weren't able to show it today. I'm extremely disappointed with that but the race is tomorrow. We'll see how we go."
Stoner was unsure what to expect from Honda's race pace, as given his ongoing issues with the 2012 Bridgestone tyres, he expects the temperature to be key to his Sunday form.
"To be honest, it depends on the temperature," he replied when asked about his chances in the grand prix. "We worked on the hard tyre pretty much this whole weekend, other than the first session. We've been trying to improve it, and we have made some small steps.
"We still need a couple of tenths before we feel really confident for the race tomorrow. But if it's cooler temperatures, we've got the pace with the soft tyre."
Dani Pedrosa qualified third on the second Honda, falling away from the pole battle as Lorenzo and Stoner raised the pace. But Pedrosa remained optimistic about his race chances.
"I was working on many things all through the session - trying tyres and trying some set-ups on the bike - because we lost this morning's practice, so it was quite a busy time," he said. "Towards the end, I wasn't able to beat my laptime from the beginning.
"But I'm quite confident anyway, I think we did quite a good job this afternoon."