Charl Schwartzel still isn't sure how he did it. The intercostal muscle he tore at the U.S. Open wiped out most of his season in 2012.

Schwartzel has been playing pain-free for only the last month and a half after the injury contributed to problems with his swing. But signs are there that he's nearly back to his best and maybe ready to challenge two-time defending champion Lee Westwood at the Nedbank Golf Challenge at Sun City this week.

Schwartzel says on Wednesday his game is "definitely on the way up." A tie for third at the World Tour Championship in Dubai last weekend helped his confidence.

Westwood won a second straight Nedbank title last year with a third-round 62 and has been solid at the Gary Player Country Club.