Rafael Nadal and Novak Djokovic won their matches for their respective countries on Day 4 of the ATP Cup on Monday.
The hosts had blanked Germany in their opening tie and became the first to seal a quarter-final spot with their second 3-0 win in the inaugural team event.
Apostolos immediately got up from his chair in shock and went up to the stands to sit with the rest of the Greek team while Tsitsipas, who was docked a point and warned by the umpire, received an earful from his mother Julia Apostoli.
World number one Rafael Nadal won a battle of attrition against fellow left-hander Yoshihito Nishioka of Japan 7-6(4), 6-4 to seal Spain's spot in the final eight of the inaugural ATP Cup in Perth on Wednesday. Meanwhile his long-time rival, world number two Novak Djokovic, had an easier outing in Brisbane, strolling past Chile's Cristian Garin 6-3, 6-3 to stay undefeated in the new year.
Organisers played a wrong national anthem for Moldova ahead of their tie against Belgium in Sydney. Denis Shapovalov won the battle of the next generation against Greek Stefanos Tsitsipas to help Canada to an emphatic 3-0 victory in the inaugural ATP Cup men's team event in Brisbane on Friday.
The 23-times Grand Slam champion looked a completely different player from the person who smashed her way into the semi-finals of the doubles with Caroline Wozniacki on Wednesday but managed to do just enough to beat the 86th-ranked McHale.