The Alfa Romeo driver has been quick throughout the weekend, finishing fourth fastest in the first part of qualifying and fifth in Q2 before eventually netting sixth in the top 10 shoot-out to split Ferrari duo Carlos Sainz and Leclerc.
The Finn is now in prime position to help Alfa Romeo consolidate sixth place in the constructors' standings ahead of Aston Martin and Haas whose four cars are at the rear of the grid.
"It was a good day, and surprising," said Bottas. "We have seen from the beginning of the weekend that we seem strong and I felt comfortable.
"So we thought with a good quali we should be able to fight for seventh place but to split the Ferraris is an added bonus."
Alfa Romeo set off "on the right foot" - Bottas
Alfa Romeo added an upgrade at the United States Grand Prix last weekend that produced instant results, only for Bottas to spin out of the top 10 at COTA.
With the performance continuing a week on, Bottas insisted: "We didn't add anything from Austin to this weekend.
"I was thinking before the weekend the layout could be good for our car, but it seems to be really good for our car.
"The slow-speed corners, we seem pretty strong, over the kerbs, through the chicanes, the car feels quite nice so it suits this track.
"Then the starting set-up for the weekend, we have only had to do small fine-tuning so we started on the right foot and have been able to build on that."