Henrik Stenson tightened his grip on the Race to Dubai title as nearest rival Danny Willett's recent struggles continued in the Nedbank Golf Challenge in Sun City.

British Open champion Stenson can end the season as European number one for the second time in four years with victory in South Africa, provided Willett finishes outside the top 10.

And the 40-year-old Swede found himself just a shot off the lead following an opening 69 as playing partner Willett could only card a 75, his 10th score over par in his last 12 rounds.

“I’m very pleased,” said Stenson. “It was below average on the front nine and I hit a good shot into eight and drained a nice birdie putt on nine to turn in red figures.

“I hit it nicely on the back nine and rounded off with some good birdies on 15, 16, 17 and a good par save on last. I’m very happy with that round.

“It would be nice to wrap up the Race to Dubai, but I just want to play as well as I can for these two weeks and see where it takes me.

“Of course you’re always going to look a little bit and see what the other guys are doing, but at the end of the day I’ve got to focus on my game and I managed to do that, so I’m happy with today’s work.”

Willett had topped the money list since winning his first Major title at the Masters in April, but was overtaken when he could only finish 75th in the 78-man field in the WGC-HSBC Champions in Shanghai, where Stenson was joint second.

Stenson did not contest last week’s Turkish Airlines Open, but Willett finished joint 68th in Antalya to only reduce his deficit from 261,387 to 252,163 points.

Willett got off to the ideal start on Thursday with a birdie from five feet on the first, but ran up a triple-bogey eight on the second after a wayward approach which forced him to take a penalty drop on the third tee.

From there the 29-year-old found a greenside bunker and needed two attempts to escape, before further bogeys on the third and eighth completed a front nine of 40.

The world number 11 carded three birdies and two bogeys on the back nine to finish three over par, seven off the lead shared by compatriot Ross Fisher, Chile's Felipe Aguilar and Korea's Wang Jeunghun.

Fisher was four under par after 10 holes and was delighted to recover from his only bogey of the day on the 17th with a birdie on the last.

“I was working my butt off to birdie the last I have to say,” Fisher said. “I wanted to try to make birdie because I let a few chances slip on the back side.

“I’m still of the mindset to go out there and attack and try and make as many birdies as I can and try and shoot as low a possible score that I can.”

Stenson was part of a seven-strong group on three under which included Scotland's Richie Ramsay, home favourite George Coetzee and England's Chris Wood, who had looked in danger of pulling out after his opening tee shot.

“Honestly that’s probably one of the best rounds I’ve ever played,” said Wood, who finished third last year after being put on a drip due to suffering from dehydration before the event.

“I couldn’t really move my head this morning and I had sort of a recurrence of the neck injury that ruined my summer really. It was completely random. With very strong tablets it becomes easier and it does help once you’re out there.”

Ramsay carded six birdies and two bogeys on his tournament debut and said: “I really love the golf course here. You’ve got to drive it well, which I did today. That gave me lots of chances coming into the greens.

“I just need to sharpen up the short game a touch, and bring it into tomorrow and then chase another good score.”

Pádraig Harrington endured a tough opening day, going out in 41 shots as he closed the front nine bogey, bogey, double-bogey.

Birdies on the 11th and 14th got him back to three over but a bogey five on the 17th left him with an opening round of four-over 76.