Adam Scott has bolstered his new world No.1 ranking by winning the US PGA Tour’s Crowne Plaza Invitational.

Adam Scott feels he’s proved a point after shoring up his new world No.1 ranking with a victory that took him past some of golf’s greatest names as the first to claim the Texas Slam.

Scott defeated fellow major winner Jason Dufner on the third hole of a sudden-death playoff to claim the Crowne Plaza Invitational title at Colonial Country Club on Sunday.

Critics had claimed Scott’s rise to No.1 was the less impressive because it occurred when he was not playing last week, spurring the Queenslander to join the field in Fort Worth.

And the 33-year-old Australian showed class befitting the world’s best player by fighting back from a four-over opening nine holes on Thursday to win on Sunday, boosting his rankings lead.

“It’s a good feeling and maybe some validation you could say,” said Scott, after becoming the fifth Australian winner on the US tour in 2014.

In doing so he went past greats including Ben Hogan, Byron Nelson, Sam Snead and Arnold Palmer, who all won three of the US tour’s four Texas events but never clinched the full set of Byron Nelson, Texas Open, Houston Open and Colonial titles.

Scott and Dufner both fired final round four-under-par 66s to finish locked at nine-under, forcing the play-off.

When he teed off in the final round, Scott was tied 16th and knew he needed to finish inside the top 13 to hold onto the No.1 ranking following world No.3 Henrik Stenson’s tie for seventh on the European Tour.

By the time he made a clutch 14-foot putt on the second playoff hole for birdie and then a seven-foot winner the next hole, he had opened up a handy rankings cushion that will make him hard to topple before next month’s US Open.

“I guess it’s a new experience. It was certainly on my mind,” said Scott of the rankings battle.

“I was having to speak about it a lot this week, leading up to teeing off and maybe added a little pressure for myself, trying to play like a number one.

“But I think the important thing was I realised that didn’t mean playing perfect.

“The way I came back and got it done, I felt like I certainly played like one of the best players in the world out there.”

While he completed the Texas Slam by adding to his 2007 Houston Open, 2008 Byron Nelson Championship and 2010 Texas Open he already has his sights on a career major championship grand slam.

Right now his 2013 Masters win is his only major title.

“I really wanted to win them all here in Texas,” said Scott.

“I think that’s a pretty neat deal, the Texas slam, that’s a good slam to start with.

“I’ll see if I can find some kind of other slam eventually in my career but to start here is a great.”

Rounding out a great day for the Australians, John Senden finished tied fifth and clinched a US Open start through his world ranking.

The Queenslander is now exempt for the remaining three majors of the season.

Matt Jones can also celebrate a place in his first British Open and a second US Open but the news wasn’t as good for Marc Leishman.

The Victorian fell from one off the lead starting the final round to a tie for 21st with a two-over 72, leaving him a birdie or two away from getting to the US Open on world rankings.