The latest rankings released by the ATP on Monday has Klaasen moving up from 23rd position to 20th after reaching the doubles quarterfinals with American partner Eric Butorac in the US Open.
In the process, the 31 year-old improved on his previous best ranking of 22nd, in spite of the defeat against the American pairing of Scott Lipsky and Rajeev Ram last week.
Klaasen and Butorac have also now improved their chances of making it into the ATP’s year-end World Tour Finals in London, being two spots away from qualifying for the R700-million event in which the world’s top eight singles players and top eight doubles pairings participate.
“This is a memorable achievement for me reaching the top 20 mark and improving 25 places over the course of the year,” Klaasen said.
“I am also gratified by the enormous messages of support I received from South Africa before the US Open quarterfinals.”
Also improving his position in this week’s ATP world rankings is top South African singles player Kevin Anderson, who moves up from 20th place to 19th after reaching the third round at Flushing Meadows before losing to singles finalist Marin Cilic from Croatia.