The 19-year-old Spaniard reached his second Association of Tennis Professionals Masters final in five weeks and claimed his first win over a reigning world number one, overcoming Djokovic in front of a sell-out home crowd at the Caja Magica.
World number four's criticism comes as Novak Djokovic was included in the Australian Open official draw, although it is still uncertain whether the Aussie government will cancel Djokovic's visa for a second time over breaking Covid protocols.
The 6-7 (6), 2-6, 6-3, 6-2, 6-4 defeat was the first major final for Tsitsipas and 29th for Djokovic, who also won the French Open in 2016, along with nine titles at the Australian Open, five at Wimbledon and three at the US Open.