Nico Rosberg leads first Singapore practice for Mercedes

Rosberg fitted the fourth and final power unit of his allocation for first practice and put it to good use as he clocked a 1m47.995s to finish 0.319 seconds clear of Hamilton.

The world champion had made a few small mistakes, including missing the apex at Turn 2 and running wide, early on and was only fourth at first as Rosberg set the pace.

Red Bull has traditionally run well in Singapore, winning every year from 2011-13 and finishing second and third on the podium last year, and it continued that form this year with Daniel Ricciardo third, 0.017s adrift of Hamilton, having been second for a spell.

Alexander Rossi, who is making his full grand prix weekend debut this weekend with Manor, was on-course for a trouble-free session and was just 0.015s adrift of team-mate Will Stevens.

But with a few minutes of first practice remaining, the American hit the barrier at Turn 18, causing quite significant damage to the right-hand side of the car and bringing out a red flag that ended the session early.

Ferrari's Sebastian Vettel, who was fourth, got on the kerb on the approach to Turn 5 and had to abort halfway round the corner, narrowly keeping it out of the wall.

The other Ferrari of Kimi Raikkonen was fifth ahead of Williams's Valtteri Bottas and Force India's Nico Hulkenberg.

Carlos Sainz Jr was two seconds off the pace in eighth, but he pipped Toro Rosso team-mate Max Verstappen by just 0.019s.

Pastor Maldonado, whose Lotus kissed the barriers at Turn 13, completing the top 10.

McLaren has long said Singapore could be a highlight of its troubled season and the early signs were positive, with Fernando Alonso 11th quickest, three tenths quicker than Jenson Button, who encountered radio problems, in 15th.

Force India's Sergio Perez was 12th, followed by Felipe Nasr in the heavily-updated Sauber, which has been revised with 2016 in mind.

Romain Grosjean took part in first practice for the first time since Canada, having generally had to give his Lotus up for reserve driver Jolyon Palmer, and was 14th.

Marcus Ericsson was 16th in the second Sauber, ahead of Williams's Felipe Massa and Red Bull's Daniil Kvyat, who spent a lot of time in the garage after concerns over the fuel system were raised.

Humidity hit 80 per cent during first practice as the sun set in Singapore and the floodlights around the 3.147-mile Marina Bay circuit flickered on.