Lewis Hamilton has vowed he will "fight until the end" following yet another retirement this season that denied him "an easy victory".

Two wins in the last three races had firmly thrust Hamilton back into the hunt for this year's Formula One world championship.

And after grabbing pole position on Saturday for the Singapore Grand Prix, Hamilton appeared on course to make it three victories in four races, only for his McLaren to suffer a gearbox failure on lap 23 when leading.

Instead of further closing the gap to title leader Fernando Alonso, Hamilton was left to contemplate a run of four retirements in the last seven grands prix, and three in the last five.

With Alonso finishing third, the 81st podium of his F1 career to move him past Ayrton Senna and leave him with only Michael Schumacher and Alain Prost ahead of him, Hamilton trails the Spaniard by 52 points.

In taking the chequered flag for the second successive year at the Marina Bay Street Circuit, reigning champion Sebastian Vettel is now Alonso's closest challenger, moving to within 29 points.

Vettel's victory was allowed to stand despite a visit to the stewards alongside runner-up Jenson Button after it appeared the 24-year-old brake tested the Briton during the first of two safety car periods, almost causing a collision.

The stewards decided no action needed to be taken, allowing Vettel to celebrate the 23rd win of his career and move him within striking distance of Alonso.

As for Hamilton, appreciating the McLaren is clearly the best car at present given it should have made it four wins from the last four poles, the white flag is far from being raised.

Hamilton said: "It's heartbreaking not to have finished the race because I was cruising, managing the gap and I had the pace.

"It should have been an easy win, but then I started to experience a problem with the gears.

"I told the team and they told me I should be able get to the end of the race, but then I lost third gear, then all the gears went. It was gutting.''

It was noticeable Hamilton did not immediately go to the pen after returning to the garage to conduct interviews, instead waiting until after the race had finished.

That gave him enough time to calm down and collect his thoughts, so producing a positive, philosophical mood, rather than negativity and anger.

Looking ahead to the remaining six races, Hamilton added: ''The good thing we can take away from this weekend is we have extremely good pace, and as a result we can really attack.

"It's going to be hard to close the gap to guys like Fernando and Sebastian, especially when they keep finishing race after race.

"But I'll never give up. There are six more races, and I need to go and win all six. I'll fight until the end.''