The 30-year-old's comments came after emerging out victorious ahead of Mercedes driver and championship leader Lewis Hamilton in the first practice session.
However, Vettel failed to set a timed lap in second session due to heavy rain showers all-but making the afternoon a wash-out.
Despite the same, Vettel remains upbeat that Ferrari would surely turnaround their fortune in Japan.
"Obviously the results were not the best over the last couple of races but I think we are strong and I think we have all reasons to be confident," Sport24 quoted Vettel as saying.
"I'm pretty sure that on Sunday we'll be able to show what we can do. We brought some changes to Malaysia, not so much for here but it's only a couple of days later. I think overall the car is working and it's up to us to improve. I think we are on track, it's doing what we expected," he added.
The German further pointed out that the car is working really well and that it is upto them to focus on improving their performances.
"So now we just need to make sure that the results are coming.We would've loved to run a little bit more but I think we know the situation with the tyres so you never know how much running is right because you don't want to burn the tyres but overall that's how it is and it's the same for everyone," Vettel said.
With just five races remaining, Hamilton is currently standing at the top of the drivers' championship and maintaining a lead of 34 points ahead of Vettel.(ANI)