Westwood fired an eagle and six birdies in a brilliant final round of 64 at Sun City to finish 15 under par and three shots ahead of overnight leader Sergio Garcia, with home favourite Louis Oosthuizen a shot further back after a double bogey on the 18th.
The victory is Westwood’s 24th on the European Tour and his first on the circuit since April 2014, although he did win the Indonesian Masters on the Asian Tour in 2015.
And it vindicated the 45-year-old’s decision to rule himself out of the running to be Europe’s Ryder Cup captain in 2020 as he targets a record-equalling 11th appearance in the contest as a player at Whistling Straits.
“I’m a bit emotional to be honest, you’re never sure whether you’re going to be able to do it again,” said Westwood, who previously won the event in 2010 and 2011 when it was a 12-man invitational. “Still got it, I guess. Just nice to do it again under pressure and win against a couple of quality players at the end there. I can’t wait to watch the highlights to be honest because I hit so many good shots coming in.”
Westwood’s partner Helen Storey was his caddie for the week and he added: “It’s been brilliant. She’s caddied twice for me this year and we lost in a play-off in Denmark and we’ve won here. Might have to have a bit of a rethink, not least about who caddies for me, but our percentages!”
Westwood began the final round three shots behind Garcia, but made the ideal start with an eagle from three feet on the par-five second and also birdied the eighth to reach the turn in 33. Further birdies on the 11th, 13th and 14th ensured he kept pace with Oosthuizen as the pair traded blows on the back nine before Oosthuizen crucially three-putted the 15th from the back of the green.
Westwood seized his opportunity and birdied the 16th and 17th to leave Oosthuizen needing to eagle the last to force a play-off, but a wayward drive led to a double-bogey six to drop the former Open champion into third place.
“There’s not much more I could have done,” Oosthuizen said. “I made good putts. I missed a few easier putts, but all in all I attacked when I wanted to attack and I pulled a lot of good shots off. Garcia had been chasing back-to-back wins and a wire-to-wire success after an opening 64, but had to settle for second place after a closing 70.
“I didn’t have my A game, other than Thursday obviously, but I fought hard,” Garcia said. “I’m thrilled for Lee. He had a bad Ryder Cup at Hazeltine (in 2016) and he struggled a little bit, but he’s been playing much better this year.”