Serena Williams's tennis coach Patrick Mouratoglou has fuelled rumours that he is in a relationship with the world number one by posting a photo of the pair online.

Reports have romantically linked the duo, whose work together has resulted in just two defeats for the US pro this year, for some time.

Mouratoglou has done little to play down the rumours by posting a photo on Twitter of the couple arm-in-arm during Tuesday's ITF Champions' Dinner.

The pair were also spotted with their arms draped around one another in Valbonne last year.