The top-ranked Englishman sailed to a 4-under 68 in the final round at the Gary Player Country Club for a 271 total, chipping in from the fringe on 18 for a memorable birdie finish.
“It was the stuff that dreams are made of, I guess,” Westwood said of the pitch and run from nearly 40 yards that nestled in the cup for a three on the last hole and a perfect ending in front of a packed gallery.
“I didn’t want to get ahead of myself but I knew I was playing well. It was a professional round I thought. Recently, I really felt there was a good week coming.”
Westwood had five birdies and one bogey, on No. 17, to secure the top ranking for the remainder of 2010 from a resurgent Tiger Woods.
South Africa’s Tim Clark shot a 1-under 71 to finish second on 9-under 279, one better than compatriot Retief Goosen and Spaniard Miguel Angel Jimenez.
The 37-year-old Westwood has led the 12-player field since Friday and was unchallenged on the final day to win his first Nedbank title on his seventh attempt, collecting $1.25 million in prize money. It was his second tournament win of the year in his final event of the season.
He carded under-par rounds of 68, 64, 71 and 68, with four bogeys all week, in a performance befitting his top ranking.
“It (the No. 1 ranking) is something that I’m still coming to terms with,” Westwood said. “But since I’ve become No. 1 I’ve finished second (HSBC Champions), third (Dubai World Championship) and first. So, I think I can cope with it.”
Paired with Westwood Sunday, Clark rolled in a seven-foot putt on 18 to save par and clinch second place – and a check for $660,000.
“I had a pretty good idea what was at stake there (with the putt on 18),” said Clark, who bogeyed his first hole of the day and never threatened a dominant Westwood despite three birdies in his back nine.
Clark also bogeyed 17 after misreading the yardage and ending up well short of the green, but the result was not in question from the time Westwood made birdie on Nos. 9 and 10 – both long, testing par 5s – to increase his overnight five-shot advantage.
“I don’t think it would have been possible to catch Lee today. There’s no question he is the world’s No. 1. It’s not just points on a sheet. I think he has that belief right now,” Clark said.
Westwood’s final-round 68 was only matched by Goosen, who jumped from ninth to a share of third with his 4-under finish to share third with Jimenez on 8 under.
The charismatic Jimenez, who delighted South African fans all week, ended with a 15-footer for birdie and a matador-like flourish with his putter.
Ernie Els and Ross Fisher were three shots back on 5 under. Els struggled with a new putter and had two bogeys and a double bogey going out, ending with a 1-over 73 – his worst round of the week.
Fisher was hampered by a suspected stomach virus, which also struck Louis Oosthuizen and Westwood’s caddie, Billy Foster, and slumped to a 75 after being in contention Friday and Saturday.
Defending champion Robert Allenby of Australia (72) and first-round leader Padraig Harrington (75) shared seventh on 3-under 285.
South African-born Englishman Justin Rose (72) and Anders Hansen, who had three double bogeys in a 76, were 2 under.
Italy’s Edoardo Molinari slipped to 11th with his 76, and British Open champion Oosthuizen (74) was 19 shots back from Westwood’s score in 12th and last, 2 over par – although that still netted him $250,000.