SINGAPORE - Nico Rosberg led a smog-hit Singapore Grand Prix first free practice on Friday but America's Alexander Rossi had a debut to forget as he smashed his Manor car into the barriers.Rosberg was in front throughout the dusk session, clocking a quickest lap of 1min 47.995 sec to lead his record-seeking Mercedes team-mate Lewis Hamilton by more than three-tenths.
It was an early statement from the German, who desperately needs a win this weekend to preserve his slim chances of lifting the world title.
Hamilton, 53 points clear in the championship, is hoping to match the late Ayrton Senna's record of eight straight pole positions, as well as his career tally of 41 wins from 161 races.
Britain's Hamilton coolly drove hands-free as he rolled down the pitlane adjusting his gloves, but it was a less than smooth session for the reigning world champion.
Hamilton, who is also in sight of a Senna-equalling third world title, had to abort one quick lap when a savage twitch took him within a whisker of the barriers.
Daniel Ricciardo was third fastest in the session for Red Bull, ahead of his former team-mate Sebastian Vettel who also had some hair-raising moments in his Ferrari.
Vettel twice brushed the walls before late in the session he overshot a corner and had to break hard to avoid ploughing nose-first into the barriers.
Rossi, brought in only this week in favour of Roberto Merhi, was just minutes from an error-free debut until the wheels came off -- literally.
The first American to drive in F1 since 2007 was heading down a straight when he hit the wall hard, leaving both right wheels askew.
Smog caused by Southeast Asian forest fires had abated after heavy rains but it returned for the session, hitting unhealthy levels according to official figures.