Rory McIlroy is confident that he is capable of securing a second major title in the space of four weeks when he competes in the US PGA Championship this week.

The Northern Irishman has travelled to Valhalla feeling on top of the world and at the summit of the world rankings, having risen to that position after winning his first World Golf Championship event - the Bridgestone Invitational - on Sunday.

It is the third time the Open champion has taken top spot with a win - and the first time that he has topped the rankings at all since March last year - the first coming after the Honda Classic in March 2012. McIlroy also returned to the world No.1 spot later that year when he won the US PGA Championship by eight shots at Kiawah Island.

That was one of five victories which allowed McIlroy to finish top of the money list on both sides of the Atlantic, but the 25-year-old feels his Open triumph at Hoylake and victory at Firestone Country Club - both by two shots over the unfortunate Sergio Garcia - has meant that he is playing at a higher level.

"This is better," said McIlroy. "I'm more in control of my ball and my ball flight. Mentally, I'm really sharp.

"It was the most comfortable I've ever felt trying to close out a golf tournament out there [on Sunday]. I felt normal. I felt like it was the first round or the second round. It didn't feel like a fourth round.

"When I say mentally it's the best I've ever been, I didn't get ahead of myself. I didn't start to think about my score. I didn't think about where I was in the tournament. I just kept playing my shot after shot after shot."

With Adam Scott failing narrowly to secure the top-five finish he needed to prevent McIlroy from overtaking him, the Northern Irishman's lead at the top of the rankings is just 0.17 points. However, McIlroy is more focused on tournament victories than rankings, with plenty still to play for in the rest of the season. "If you win tournaments, the ranking takes care of itself," he added.

It has been left to others to ponder how equipped he is to remain as the No.1 player in the game, perhaps even dominating like Tiger Woods did in his prime. "There is no reason why he cannot," said Paul McGinley, the European Ryder Cup captain. "What I think is great is that Rory can hold his attitude where it is at now."