Daniel Ricciardo said the new Circuit of the Americas had lived up to expectation after sampling the track for the first time in Friday practice ahead of the United States Grand Prix.

Ricciardo was the fastest of the two Toro Rosso men across the two sessions on Friday with the 15th quickest time on the combined timesheets.

Speaking after the two sessions, the Australian admitted that the lack of grip had made conditions challenging on track but said the circuit was one that had lived up to the hype.

"The new track lived up to the expectations we had before coming here, although the lack of grip spoilt it a little bit," he said. "But as the track rubbers-in and cleans up, I'm sure it will get even better. The grip level did improve from morning to afternoon but I'd expected a bit more. In fact I reckon next year, we could find a completely different circuit, although by this Sunday I think it will be much more fun.

"The slippery conditions meant it was difficult to understand what our car was doing. We improved it from the first to the second session, but we need to keep on down doing that tomorrow. The tyres are taking a long time to warm up and that is one of the most complex aspects of the package that we must look at. It will definitely be an important factor tomorrow afternoon in qualifying."

Team-mate Jean-Eric Vergne, who was involved in a clash with Heikki Kovalainen that saw him forced to change his front wing, was also full of praise for the circuit having finished the day one place further back.

"I have to say this is a really nice track and I like it very much," he said. "It is very challenging with a lot of places where you can overtake, even without DRS I can see some corners where you can pass, which will be good for the show and it is also excellent purely from a driving point of view. There was not one corner where I felt it wasn't interesting.

"Technically, it was quite a difficult day, because this morning there was no grip at all, but I'd say we maybe look a little bit better than at the previous grand prix. We saw some interesting things on the data today and I am sure we can have an okay day tomorrow."