Follow live coverage of FP2 and the rest of the United States Grand Prix weekend from Austin with F1i.
The start of the session has been delayed "indefinitely" at the Circuit of the Americas, with "marshals unable to work due to the proximity of lightning".
After a wet opening session which was topped by Nico Rosberg, there is likely to be less running in FP2 as heavy rain has struck the Circuit of the Americas. Most teams tried to get in some mileage during the first session in the knowledge of deteriorating weather.
Rosberg was fastest in the opening session by over a second over the Red Bull pair of Daniil Kvyat and Daniel Ricciardo, although Mercedes, Red Bull and Ferrari all limited their running.
McLaren was the busiest team in the first practice session as it is running two different specification of power unit on its cars this weekend, with Fernando Alonso using the new engine for a full race weekend for the first time.
Lotus changed its driver line-up plans during the race weekend, with Jolyon Palmer taking over Romain Grosjean's car for FP2 rather than the opening session in order to allow Grosjean the opportunity to drive in the better conditions.
You can follow all the live coverage on F1i's live page, which can be bookmarked as it will provide commentary on every session of the 2015 F1 season.
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