Gael Monfils was issued a unique warning at the Citi Open on Wednesday after he walked toward his bench mid serve.

Osaka and Monfils lost to Caty McNally and Lorenzo Musetti in their opening mixed doubles match at the US Open.

The Italian left the court for a change of clothes before the decider and broke Monfils’ serve twice after his return to jump to a 4-0 lead in no time.

Monfils quickly won a second-set tiebreaker, then held serve throughout the third set to finish off a 4-6, 7-6 (5), 6-4 victory over the reigning Cincinnati Open runner-up.

Jack Draper fails to return a Gael Monfils serve and the Frenchman turns to his coach and says "wow". Wow, indeed, Gael. Monfils goes on to hold and Draper will serve for the set.