Security personnel acted quickly to pull the man out of the “O2” stadium, before resuming play after quickly examining the floor undamaged by the strange incident.
British media reported that the protester is a member of the “Stop Private Jets UK” group that says 2022 carbon emissions are genocide.
Tsitsipas went on to win 6-2, 6-1 to give Team Europe a 2-0 lead against the rest of the world, after Kasper Rudd previously defeated Jack Sock 6-4, 5-7, 10-7.
Roger Federer will appear on the field later on Friday for the last game of his career.
The 41-year-old is expected to compete against his great rival, Rafael Nadal, against American doubles Sock and Francis Tiafoe.