While not ruling out other contenders, Button feels that Red Bull will continue its strong street track form.
When the 2009 World Champion was asked if Vettel was going to be his main rival at the Marina Bay street circuit this weekend, Button said: "Apart from my team mate, yes. Sebastian has been consistently quick here. Red Bull seem to be very good on street circuits and they have been all year."
The 32 year old Englishman expects Spanish Ferrari driver Fernando Alonso also to be a factor. Button was particular impressed with the long-run pace of the current Championship leader, meaning that the Ferrari could be a force to be reckoned with on Sunday in particular.
"I don't think Vettel is going to be the only person that's competitive. Fernando will be up there as well," Button said. "His long runs look reasonably competitive. I think they'll be good."
He added that the unpredictable nature of F1 this season means that a team that struggled on Friday could still get into contention later in the weekend.
"You never realy know in F1 these days. Maybe Sauber will spring an attack from nowhere. The Lotuses I see were not happy yesterday but that can easily turned around today," Button added.
Button's team mate Lewis Hamilton said on Friday that he was happy with the handling of his car, while Button has still work to do on the balance of his car.
