Liberal MP John Alexander has apologised for a bizarre anecdote he relayed while claiming victory in the Bennelong byelection, which drew fire from disability advocates.

On Saturday night Mr Alexander, while standing next to a beaming Prime Minister, Malcolm Turnbull, told a story about someone who had come up to tell him that he had built Tennis World, a tennis complex.

Mr Alexander said that when he thought his tennis career was over, his back improved when he started coaching at the centre.

"Then I got to about No.14 in the world," said Mr Alexander, who will be returning to Parliament as the holder of a seat he first won in 2010.