By Tim Wharnsby

OAKVILLE, Ontario (Reuters) - Jason Day is eager to open defense of his title at this week's Canadian Open, where his triumph last year marked the start of a remarkable run that saw him win his first major title and claim the world number one ranking.

When Australian Day arrived at the Glen Abbey layout a year ago he was still stinging from a missed putt that would that would have put him in a four-way tie for a playoff at the British Open and shot at major championship glory.

But rather then let a missed opportunity days earlier get him off his game, a focused Day ended the Canadian Open in style as he made three closing birdies to beat Bubba Watson by a stroke for his second title of the season.

The victory marked the start of a red-hot run by Day, who won four of six events, including the PGA Championship and two of the FedExCup playoff tournaments.

"I always thought I could play golf like this," said Day, who will tee off in Thursday's opening round outside Toronto at 8:10 a.m. ET (1210 GMT) alongside Brandt Snedeker and Ernie Els.

"It's been a crazy last 12 months," Day said. "I've always talked to (caddie) Colin (Swatton) about it, that's exactly what I should be doing, and once again, I can't get too complacent with where I'm at.

"I know that I'm currently ranked the best player in the world, but I need to work hard. I need to work harder than I ever have before to keep that spot. I need to work harder than I ever have before to win tournaments, because it's only getting tougher."

Day's last win was at the Players Championship in May. He finished joint eighth at the U.S. Open last month and tied for 22nd at last week's British Open.

The 28-year-old Day, who next week will open defense of his PGA Championship crown, knows a player like U.S. Open champion and world number two Dustin Johnson has closed the gap.

“I just want to win again,” Day said. “I'd like to win everything from here on in.

“I feel very motivated right now with how (Johnson) is playing. He's playing tremendous golf currently, and he's on the heels. He could play well here in the next few weeks and take over my spot, so I don't want that to happen.”

Johnson is also in the field at the Canadian Open and will be full of confidence after his win at Oakmont last month and the WGC-Bridgestone Invitational two weeks later.

"One of the things is, especially when I'm teeing it up in a major, I'm not still trying to get that first one," Johnson said. "I know what it takes, I know I've got what it takes to get it done. That obviously gives me a lot of confidence when I'm out there playing."

(Editing by Frank Pingue)