The momentum is now with Hamilton with the Briton having won three of the last four races (Italian, Belgian and British grands prix) to snatch the championship lead from Vettel at Monza.
Bottas has won two races this year and has 197 points, while Hamilton (238 points) and Vettel (235) have 10 victories between them.
"I've been here for quite a few years now and I think next year we need to make a bigger step than we did this year, to really convince me that I can win with them".
Meanwhile, at Belgium's Spa Francorchamps, Mercedes were expected to dominate but Vettel remained in hot pursuit of Hamilton all the way through the race. "It's kind of just arrive and do, and I want to do the best the whole time".
"For my part I know I have to perform but it's always been like that in my career".
Drivers must get the timing just right as they approach at a top speed of 320 kilometers (198 miles) per hour before braking heavily down to 120 kph (74 mph).
Ferrari, on the other hand, have been in a class of their own when the power unit is not as crucial at high downforce circuits, sealing dominant one-twos in Monaco and Hungary.
And despite Mercedes winning the last two races, Vettel says Ferrari is relishing being in such a fight after having struggled to win races consistently for a number of years.
"We looked very strong", Verstappen said.
The Finn trails his teammate Lewis Hamilton and Ferrari's Sebastian Vettel by 38 points, and he said he needs to get his act together quickly.
Daniel Ricciardo was the man who went fastest in Singapore in both of the Friday sessions.
This is a vehicle which caused Mercedes considerable angst in Monaco, with Ferrari in a different pace league all weekend at the Principality.
"We have taken an engine early to have the performance gain", Wolff said.
"I go with what we have, what I will feel tomorrow at the track and the auto that I have then under me", said Vettel. The anticipated temperatures in Singapore reaching 86 degrees Fahrenheit with 86% of humidity at the time of the race. For Red Bull, it is one of the best chances to secure a race win after Daniel Ricciardo emerged out as the surprising victor of the Azerbaijan Grand Prix.