"Normally long runs are a forte of mine and it wasn't today," he told reporters. "The problem is I can make the soft tyre last for one lap and that's it. The degradation is massive, so it feels that something isn't quite right on my car.
"There's got to be something that's not working," he added, "we'll be changing quite a lot of stuff for tomorrow."
"Fernando has got some slightly different bits on his car than I have, but even so, we should be more competitive on the long runs than we are," he said. "We're a long way off, there's something we need to look at, something's wrong rather than a set-up issue.
"It's very close from seventh back to where I am in 16th, about four tenths," he added. "So if you get a good lap together, which hopefully I will in qualifying, we could be popping into the top ten.
"I'd love it to rain," he admitted, "that would help us have a chance of a good result."