The US Tennis Association (USTA) is warning folks: "No Bryan Brothers chest bumps."
That was among the suggestions from the USTA on Wednesday, when it offered return-to-play guidelines to help players and people running tennis facilities know when " and how " the sport should resume at the amateur level as coronavirus lockdown restrictions ease.
The USTA thinks it will be safe to again play tennis "in some cities and states sooner than in others."
One of the recommendations is to maintain social distancing by staying 6 feet apart from other people " and, therefore, to avoiding playing doubles, because it "could lead to incidental contact and unwanted proximity."
The group that runs the US Open went on to add: "If you do play doubles, avoid all incidental contact, no Bryan Brothers chest bumps and no whispering to each other from a close distance to strategize."
American twins Bob and Mike Bryan have won 16 Grand Slam titles in men's doubles together and celebrate wins by jumping simultaneously and bumping chests.
All professional tennis has been suspended at least until mid-July. The US Open is still scheduled to begin main-draw play in New York on 31 August.