South African Jbe Kruger took advantage of a collapse by compatriot George Coetzee to race clear in the Alfred Dunhill Championship at Leopard Creek today.
Coetzee, the only member of the world's top 100 taking part, led by four but then dropped five shots in the last three holes of his second round.
Kruger, also chasing a maiden European Tour victory, stepped in to add a five-under-par 67 to his opening 64 and so reached halfway on the 13 under mark of 131.
The 25-year-old is four ahead of England's Seve Benson, Scot George Murray and Chilean Felipe Aguilar.
As for Spaniard Pablo Martin, winner of the title the past two years, he suffered the embarrassment of finishing 155th and joint last after nightmare rounds of 81 and 82.
They were played alongside Coetzee, who was sailing on smoothly until he found water on the short seventh, his 16th.
After taking five there he duffed a chip on the next and double-bogeyed again, then failed to get out of a greenside bunker at the ninth and dropped another shot.
Former Zambia and Zimbabwe Open champion Kruger has missed the cut in the event the last three years, but this time has already amassed two eagles and 12 birdies.
Benson had kept pace in the first round, but had to settle for a second-round 71.
At 163rd on this season's Tour money list he faces a huge weekend. Only a victory will secure his card for next year.
Murray has no such worries after finishing joint third with Graeme McDowell in the lucrative Dunhill Links championship at St Andrews last month.
The 28-year-old from Anstruther started that week 183rd on the Order of Merit and found himself playing with Luke Donald in the final round, but outscored the world number one by three and quadrupled his 2011 earnings.
He added a 69 to his first-round 66 this time, while Aguilar, winner of the 2008 Indonesian Open, had a best-of-the-day 64.
"As long as you put yourself into contention then you are going to have a fun weekend," he said.
Former Ryder Cup player Oliver Wilson, on the other hand, missed the cut on three over and at 132nd on the money list could need a top-10 finish at next week's South African Open to keep his Tour career afloat.
It is only two years ago that the Mansfield golfer was the circuit's seventh-biggest earner with almost £2m. The nine-time runner-up has earned less than a tenth of that this season.