Santos, who was the European Tour rookie of the year in 2012 after winning his first title on home soil in the Madeira Islands Open, fired nine birdies and no bogeys to finish nine under par, two ahead of Garth Mulroy, Rhys Davies, Richard Bland and Lucas Bjerregaard.
Scotland’s David Drysdale was among a six-strong group another shot adrift on six under on a day when 91 players broke 70 and 110 of the 156-strong field finished below par.
“I played really solidly today and gave myself a lot of chances for birdie, and I took a lot of those chances,” Santos said. “I’m very pleased to make a run like I did today.
“I hit the ball solidly from the tee and my putting was all good. To shoot minus nine you have to play awesome golf, so I’m really pleased with every piece of my game.
“If the wind blows, this is a very tough course but today, if you put the ball in the fairway, you had the chance to shoot a low round. Today was definitely one of my best rounds of golf so far. I put the ball very close, didn’t miss a fairway, and that’s the key on this course.”
Mulroy was leading the South African contingent out to maintain their remarkable dominance of events on home soil.
George Coetzee’s win in the Joburg Open on Sunday means nine of the last 12 European Tour events staged in South Africa have been won by home players, with all four previous Africa Opens won by South Africans.
And, although Coetzee was not in East London after withdrawing in order to prepare for next week’s WGC-Accenture Match Play Championship in Arizona, Mulroy took up the mantle with an opening 64.
Mulroy carded six birdies, an eagle and one bogey to finish seven under par, while Davies recovered from a bogey on the first to fire eight birdies in his last 16 holes. Bland produced a flawless round containing an eagle on the third and five birdies in a back nine of 30 as the players took advantage of the calm conditions on the 6,632-yard course – extremely short by modern standards.
And, with no wind blowing in from the adjacent Indian Ocean, a repeat of the winning total of 27 under recorded by former Open champion Louis Oosthuizen in 2012 is possible. “It’s always nice to start the week this way,” Mulroy said after his round. “Usually we don’t get weather like this here, but I’m not complaining. The scores are definitely out there, you’ve just got to make some putts.”
Davies, 28, won the Hassan Trophy in 2010, beating Louis Oosthuizen by two shots just four months before the South African would go on to win the Open at St Andrews by seven. He then lost in a play-off in the same event 12 months later, but Davies has struggled to find that form and lost his card at the end of 2012.
“I haven’t had the greatest form over the last couple of years, so it’s really nice to have a good round under my belt,” he said. “It was a lovely start this morning, I enjoyed it, and I’ll try to do the same tomorrow. There are plenty of choices out there.
“You can be quite aggressive at times and more conservative at others. Lots of risk and reward, which makes it exciting to watch and good to play.”