Johannesburg - Top South African tennis player Kevin Anderson made a disastrous return to the ATP circuit when he was knocked out in his first game at the Atlanta Open by unfancied Thiemo de Bakker on Friday.
The 25-year-old Dutchman, ranked 142nd in the world, beat Anderson 6-4, 7-5 after converting three of his 13 break points.
It was Anderson's first game since he was beaten by Andy Murray in the last 16 round at Wimbledon almost four weeks ago.
"I think he played extremely well. He is certainly at a higher level than you would expect from someone ranked 142nd," Anderson said of De Bakker.
"But I was disappointed with my own performance. My usual, effective serve was not working smoothly and I felt I was battling and had my back to the wall from the outset.
"These kind of setbacks happen on the extremely tough and competitive ATP circuit and you just have to accept them and look forward to the next tournament to make amends."
The defeat may have an adverse effect on his current, career-best world ranking of 17th when the new ratings are released on Monday.
De Bakker might have won even more comfortably had he capitalised on a spate of inviting break-of-service opportunities.
"It's a great feeling to beat a top-20 player again after a relatively disappointing last year," said De Bakker.
Anderson will surrender the runners-up ranking points he received for reaching the final in the tournament last year, when he was beaten by John Isner.
The result may lead to several players, among them Tommy Robredo, Mikhail Youzhny and Fabio Fognini, overtaking the 28-year-old Anderson on the ATP world rankings.