Danny Willett makes strong start to Nedbank defence as ailing Henrik Stenson leads with Jaco van Zyl

On the eve of the Sun City event, the Sheffielder stated that he wanted to see how he could “cope with the pressure of pitching up to events as one of the favourites and expecting to win”.

As well as lifting the Nedbank title, Willett also won the Euro Masters on his way to finishing second to world No 3 Rory McIlroy in the 2015 Race to Dubai, which finished just a couple of weeks ago.

Birdies at the first and second holes on day one at Sun City, followed by another at the fifth, quickly suggested he remains in the form that saw him bank €3,670,310 in prize money.

He also birdied holes 10 and 15 on his homeward nine and stands third, one off the lead shared by playing partner Henrik Stenson, of Sweden, and South Africa’s Jaco van Zyl.

British Masters champion Matt Fitzpatrick is tied sixth after handing in a card for a three-under-par 69.

After a week’s break back home in Sheffield, he started well with birdies at the second and third holes before six consecutive pars took him to the turn in 34.

He began the inward run with a birdie at the 10th only to surrender the shot gained at the 15th.

However, the 21-year-old picked up another shot to par at the last and will be pleased with his opening round as he looks to maintain his place inside the world’s top 50.

He is currently 48th and if he remains in the top 50 come the end of the calendar year will achieve one of his season’s aims, namely being invited to play Augusta next April for the Masters, the first major of 2016.

Fitzpatrick will close his tournament year next week when he competes in the Thailand Championship, at Amata Spring Country Club, in Chonbur.

World No 20 Willett said: “Because it’s at the same golf course (as he won on last year), people expect you to play well again, but everyone knows how fickle this game can be.

“The course does set up well for me, but that doesn’t mean you’re going to shoot 67 every time you play it.”

Stenson finished joint last when seeking a hat-trick of victories in the DP World Tour Championship a fortnight ago, admitting his mind was “not in the right place” at the end of a long year, and arrived in South Africa suffering from flu.

But the 39-year-old carded a flawless 66 to finish six under par alongside local favourite van Zyl.

“I’ve been in bed with the flu for three days and after I had to pull out of the pro-am on Tuesday I probably had a five per cent chance of playing,” said 2008 champion Stenson, who is also due to undergo a minor knee operation next week.

“I felt quite a bit better this morning and the doctor didn’t see any reason why I couldn’t play.

“I’m delighted with the score, but the last few holes I completely ran out of energy. From the 14th onwards my legs were like jelly and it was a real struggle. I missed a couple of chances coming in, but I would’ve taken one under standing on the first tee, so I’m very happy.

“This year the rough is a bit less penal, but you still have to be very accurate off the tee and precise with your iron shots.”

Van Zyl has won 13 times on the Sunshine Tour, but admitted he was feeling the pressure on his tournament debut, adding: “I could feel my heart beating in my throat on the first tee. This is Africa’s major.”

The 36-year-old birdied three of the last five holes to book his place with Stenson and Willett in the final group on Friday, with fellow South African Branden Grace and Open runner-up Marc Leishman two shots off the pace on four under.

Stenson’s playing partner Willett said: “I don’t think he can be ill. He played brilliantly. I think he got very tired towards the end there, but he played tremendous golf.

“Looking at that, you’ve got to think that if you can stay close to him over the next few days you’ll be doing well. Not too close though, he can keep his virus away.”

Last year’s runner-up Ross Fisher, Fitzpatrick and Russell Knox are three shots off the pace on three under, Knox making his first appearance as a full European Tour member.

The 30-year-old Scot is hoping to qualify for his Ryder Cup debut at Hazeltine next year and would have earned more than 1.2m points in qualifying if he had been a Tour member at the time of his breakthrough win in the HSBC Champions last month.

“I missed a few putts I should’ve made, but I holed a few nice ones and had two flukey chip-ins, so overall I’m pretty happy,” Knox said.

“This place is incredible; it’s a shame we have to play golf, there’s so many activities to do. I’m looking forward to spending two days after the tournament going on safari. Yesterday we went zip-lining which was a blast, 75mph down a wire – I can’t believe I survived.

“The number one reason I’m here is because I’ve had a great season, so it’s nice to reward myself. It’s a huge bonus and I’m not going to stress out here.”