Johannesburg - South Africa's top tennis player Kevin Anderson has dropped one place to 21st in the latest ATP World rankings released on Monday.
Scraping through the first round of the Australian Open on Monday, Anderson beat Czech Republic's 82nd-ranked Jiri Vesely 2-6, 6-7 (4/7), 6-4, 6-4, 6-4, in his opening match in Melbourne.
He is in danger of dropping further in the rankings unless he progresses through to the fourth round in Melbourne.
The big-serving Anderson has been struggling on the ATP tour, failing to make it beyond the second round in his last ten events.
Last week, he crashed out of the opening round of the Auckland Open, losing 7-5 6-4 to America's Steve Johnson.
Meanwhile, Raven Klaasen continued his rise in the men's doubles rankings moving two points up to position 45.
In wheelchair tennis, Evans Maripa retained his 15th place in the men's singles rankings, while Kgothatso Montjane moved up two places to sixth.
Lucas Sithole retained his second place in the Quads singles rankings.