Sebastian Vettel said he believed Ferrari had rediscovered their form and were back among the front-running teams after Fernando Alonso topped the times in Friday afternoon's second free practice session ahead of Sunday's Canadian Grand Prix.
The defending triple world champion said he felt the scarlet scuderia, with widespread support in Montreal, would be hunting victory again.
Ferrari endured a disappointing Monaco Grand Prix two weeks ago when Alonso was only able to finish seventh.
But the two-time champion Spaniard topped the times ahead of Briton Lewis Hamilton of Mercedes, leaving Vettel admiring their rediscovered pace.
He said he also felt that Monaco winners Mercedes, who have started from three successive poles, will also be a threat through either Hamilton or Monaco winner German Nico Rosberg. Or both.
Vettel said: "On one lap if you look at the timesheets, Mercedes was again very, very quick.
"And Ferrari looks competitive on both long and short runs, so I think those will be the main two rivals. Never forget the Lotus because they can be a surprise in the race by going further (on tyres) than anyone else.
"So, for this race, it is difficult to say, but you need to keep an eye all these teams I mentioned."
Vettel's Red Bull team-mate Australian Mark Webber, who was fourth fastest while Vettel was down in seventh, said: "On the short run we have some room for improvement and Mercedes looks very, very quick again.
"But I felt we were pretty strong overall. In the wet on the 'inters' I felt comfortable straightaway. It is always tricky around here to get everything together in those conditions, if you are not comfortable you can bleed a lot of lap time but the car seemed good."