Alex and Sofia Kenin have been celebrating her victory (Photo: AFP/Greg Wood)

MELBOURNE: It wasn't so long ago that Sofia Kenin's father was driving New York taxis and spoke English so poorly that he didn't know where he was supposed to be going. These days Alex Kenin, despite starting with close to zero tennis knowledge, is coaching a Grand Slam champion.

Russian-born Alex, an unassuming, grey-haired man with a receding hairline, introduced Sofia to tennis, brought her up around the game and pushed her to achieve the extraordinary - crowned by her victory at the Australian Open on Saturday (Feb 1).