Team Europe are on the cusp of victory after building a commanding 11-1 lead heading into the final day of the Laver Cup in Boston.
Friday's opening matches had seen victories for Italy's Matteo Berrettini, Norwegian debutant Casper Ruud and Russian Andrey Rublev in Boston before Team World claimed the doubles to reduce the deficit to 3-1.
The format of the tournament, which Roger Federer helped create, sees two points awarded for a win on the second day and then three in each match on the final day meaning Europe are one win away from retaining the title.
Tsitsipas took a time out early during the second set to change his shoes, which saw Kyrgios laugh and shake his head – the Greek having come in for criticism from Andy Murray for an extended bathroom break during their match at the US Open.
The second singles match was a much closer contest, but again Team Europe clinched victory as Alexander Zverev, the German world number four, beat American John Isner 7-6 (5) 6-7 (6) 10-5 in a third-set tiebreak.
Saturday's final singles match saw US Open champion Daniil Medvedev easily account for Canada's Denis Shapovalov 6-4 6-0, with the world number two breaking his opponent's serve four times to finish the match in just 75 minutes.
The 25-year-old Russian said on court afterwards: "I played unbelievably, especially the second set.
"I didn't know what to expect because after the US Open, I didn't play for a week and a half. (I) came here, practised as much as I could the past three days, so I didn't hit many balls, but was surprisingly feeling well."
His compatriot Andrey Rublev was paired with Tsitsipas in the day's final match, with the duo faltering early before defeating Isner and Kyrgios 6-7 (8) 6-3 10-4 to push Team Europe to 11-1.