However, it wasn't long before security personnel escorted the two men out of the arena.
"When someone saw it, two of the security staff went there.
The men were escorted from their seats and then out of the arena," says Brendan McIntyre from the US Tennis Association according to TT, adding:
“There is always a first time for anything.”
Russian Karen Chatjanov beat Australian Nick Kyrgios in the quarter-finals and is thus ready for the semi-finals of the US Open.