Mirka Federer is the force behind her husband Roger's staying power in tennis

Mirka Federer, wife of Switzerland's Roger Federer, watches as her husband arrives to play against Croatia's Marin Cilic in their men's singles final match on day 14 of the Australian Open tennis tournament in Melbourne on Jan 28, 2018. Photo: AFP

Roger Federer has credited his wife Mirka with keeping him motivated and still going strong at 36, although his longevity has “many pieces to the puzzle”.

The Swiss master won his 20th Grand Slam title at the Australian Open on Sunday when he defeated Marin Cilic 6-2, 6-7 (5/7), 6-3, 3-6, 6-1.