Henrik Stenson boosted his hopes of winning the European Tour's Race to Dubai with three birdies in the final four holes to move within a shot of the lead at the Nedbank Golf Challenge.
The Open champion can win the Race to Dubai with victory in Sun City, South Africa, and he looked be gathering momentum as successive birdies at eight and nine saw him make the turn at one-under-par.
A bogey at the par-four 13th dropped him back to level par, however, the Swede - winner of the Race to Dubai and the PGA Tour's FedExCup in 2013 - posted three consecutive gains from 15 to 17 to end the day on three under.
Ahead of him on four under are the trio of Felipe Aguilar, Wang Jeunghun and Ross Fisher.
Danny Willett is Stenson's primary rival in the Race to Dubai, but the Englishman has a lot of work to do after finishing day one seven shots off the pace.
A birdie at the first was followed up by a triple bogey at the second from the Masters champion, who made the turn at four over.
Despite three birdies on the back nine Willett's progress was checked by a pair of bogeys as he struggled for consistency.
At the right end of the leaderboard at the Gary Player Country Club, Stenson is joined by six players at three under.
Chris Wood, Victor Dubuisson and Alex Noren - seeking his fourth win of the year and third in as many months - are all within a shot of the lead, as are George Coetzee, Jaco van Zyl and Richie Ramsay.
Among those struggling are Rafa Cabrera Bello, Thomas Pieters and Matthew Fitzpatrick - all members of Europe's defeated Ryder Cup team - that trio posting four-over 76s.
Another member of the unsuccessful team from Hazeltine, two-time major winner Martin Kaymer, ended the first round dead last following a dismal nine over. The German had just one birdie and shot doubles at the fifth, sixth and 17th en route to a score of 81.