Sebastian Vettel has insisted that the Singapore Grand Prix was difficult, after the Ferrari driver won the race on Sunday.

The 28-year-old finished ahead of Red Bull's Daniel Ricciardo in second and his Ferrari teammate Kimi Raikkonen in third, while championship leader Lewis Hamilton was one of five drivers forced to retire, and Vettel has acknowledge that it was a tough race to win.

"I think we were the quickest, and about the same in terms of tyre regulation compared to the Red Bulls that were very quick," Vettel told Sky Sports News after the race.

"I think it was a special race for Daniel [Ricciardo] and myself, we seemed to be the two quickest cars out there controlling the race.

"It's a difficult track, and everything needs to come together."

The next race in the Formula 1 calendar is the Japanese Grand Prix on September 27.