The US Tennis Association is warning players:"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 six 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 since March until at least mid-July. The US Open is still scheduled to begin main-draw play in New York on Aug 31.

'One of last to return'

Meanwhile, former world No 1 Andy Murray has said he believes tennis will be one of the last sports to return to action after the world has recovered from the coronavirus pandemic.

The tennis season's hiatus is playing havoc with the schedule and depriving lower-level players, who depend solely on tournament winnings, of the chance to earn a living.

"I would imagine tennis would be one of the last sports to get back to normality because you've obviously got players and coaches and teams coming from all over the world into one area," Murray told CNN.

The 32-year-old Briton, who recovered from hip surgery last year to win the Antwerp title in October, was targeting a return to the tour at the Miami Open in March after completing his rehabilitation from another hip injury.

"I would be surprised if they were back playing sport by September-time," said Murray.

Europe and the United States have been hard hit by the virus with tens of thousands of people dying across both continents.

The French Open was moved to Sept 20-Oct 4 from its traditional May start while the Wimbledon championships, set to begin in late June, were canceled.

US Open organizers said last week that playing the hard-court Grand Slam without fans in New York is a possibility but highly unlikely.

"You have to feel like the whole world working normally again and traveling normally before tennis would go back to especially the major competitions," Murray said.