Louis Oosthuizen will start this week's Byron Nelson Championship in Texas as the top-ranked player but admits he would swap that to be entering the tournament in better form.

The 2010 Open champion will head up the field at the Four Seasons Resort in Irving but has not finished higher than 10th during the 2013 PGA Tour.

Oosthuizen said he will take confidence from being the top-ranked player but it counts for little if he does not perform.

"I think that's what you make of it," he said.

"I think you probably take more confidence out of it, going into the event. I would rather come in a bit more in form than coming in top-ranked player.

"I felt like the last two tournaments I played I was getting better and I'm getting better results so hopefully the next three weeks something can happen for me."

The South African was below-par at last year's competition and feels he has struggled so far this season following initial success in the Volvo Championship.

"I didn't play very well last year when I was here and I feel like I'm playing better," he conceded. "[This season has been] a bit of a struggle, probably, started off well in Europe, in South Africa with the Volvo Championship win and not swinging the way I want to and just not getting the results I want to.

"But the last few weeks I've been working on a lot of things and it feels like it's coming together."

Tiger Woods may not be in Texas for the tournament but Oosthuizen knows the rest of the golfing world will have to step up if they are to stop the current number one re-establishing his stranglehold on the sport.

"It means we probably need to pull up our socks if we want to catch him," he said of Woods' current form.

"He's Tiger. He's an unbelievable golfer, I think no one is amazed to see him back in the form that he is. Everyone was expecting him to come back and do what he's doing."