Seven-time Grand Slam winner Williams was seen hitting with Canadian Opelka in April at the Ibis Golf and Country Club in West Palm Beach, Florida, where her tennis coach, Eric Hechtman, showed them working together.

That accelerated gossip among observers on Twitter, who also spotted that Williams left three hearts as a comment under a photo the world number 35 posted from the Italian Open in Rome earlier this month.

Hechtman appeared to indicate that the pair had traveled to Rome together in another post, and Opelka confirmed that he had been indulging his restless appetite for culture with Williams off the court.

"I was practising and I went to some art museums and art galleries," he told the ATP.

"I actually went with Venus Williams to the Borghese Museum and I got my arts and crafts in prior to checking into [the] Rome [bubble]."

A self-confessed light sleeper, inquisitive Opelka attended New York Fashion Week events around the 2019 New York Open, which was his first ATP title win.