The Australian will start alongside McLaren's Jenson Button from the third row of the grid in tomorrow's race.
The 23-year-old told Autosport.com: "For Q3 I definitely wanted to try and post a time, give it a crack and see how we went. It paid off well. If we'd been ninth or 10th it'd be a question mark, but to get seventh was really good for us.
"I think today we had to go for it. I think we surprised a few people and surprised ourselves. It all started from yesterday. We weren't extremely fast, but the way we worked was the best Friday we've had all season, the best day of testing.
"It looks like we're on the right path. We're definitely better off than we were earlier in the season."