Paul Casey feels he needs to take his career up another level by winning a World Golf Championships event.

Having won three times this year, including a maiden victory in the United States at the Shell Houston Open, world number three Casey will tee off at Firestone Country Club in Ohio tomorrow hoping to add success at the Bridgestone Invitational to two previous top-10 finishes in the event.

The tournament comes at the start of a nine-week stretch in which Casey will play seven big tournaments, including next week's USPGA Championship at Hazeltine.

The Englishman is acutely aware that there are still hurdles to clear before he can feel he is as good as he thinks he can be.

"Every tournament from here on out is very, very important," Casey said.

"World Golf Championship events are obviously a step up. That's what I've got to focus on. I've got to focus on the majors and the World Golf events.

"That's what I want to win, having kind of ticked the boxes of what I need to win.

"I've now won on the PGA Tour and lots (10) in Europe, but I need to continue to get better and win big events. I haven't done that yet, so I need to do that.

"And then we're into FedExCup and then after that right to the Race To Dubai. So there is no opportunity to back off at this point. Every tournament is crucial."

Fourth in 2006 and eighth last year, Casey feels right at home at Firestone.

"This is a golf course that I love," Casey said. "I think it's a wonderful track. It's in spectacular shape.

"It's just a great place. The staff and the clubhouse are phenomenal. This is a week I think not just myself but a lot of players really look forward to."