F1 drivers concerned about conditions for US Grand Prix

Heavy rain has lashed Austin over the last 24 hours with qualifying postponed until Sunday morning because of the conditions.

The session got underway on time, but the rain got heavier in Q2 and after initially delaying the final segment, officials chose to cancel it.

"I don't understand why he [Charlie Whiting] didn't put the red flag [in final practice] and I don't understand why they didn't put red flag at the end of the session," said Felipe Massa.

"If the conditions stay like this and it's doing this until now and the race, it will be dangerous."

When asked if he felt the conditions were dangerous in Q2, Romain Grosjean said: "Yeah, definitely.

"From the first lap in Q2, I was in traffic. I told my engineers this is getting really bad.

"Even five seconds behind car in front, you couldn't see anything. Let's hope the weather gets better."

McLaren's Jenson Button backed the decision to cancel Q3 because of the conditions.

"There were moments when it was fine like in Q1, but Q2 was questionable and because cars hadn't run, rivers started to form," he said.

"In Q2 it got too wet. I'm happy they cancelled Q3.

"Hopefully it improves for this afternoon otherwise it's going to be a lot of sitting around I think."

Mercedes' pole-sitter Nico Rosberg said: "At the moment, it's raining a lot out there. We can't drive in those conditions.

"There is still a long way to go until the race. A lot can change."

Force India's Sergio Perez added: "It's difficult to plan for the race.

"We keep a close eye on the weather as we are expecting things to be more difficult.

"At the very least I hope we can race and hope the conditions don't get poorer."