It will be a dream come true for one player on Sunday night as either Stefanos Tsitsipas or Dominic Thiem will lift their career's biggest title yet, the coveted ATP Finals trophy.
There is something that not many people know about the concerned players. When Thiem made his first appearance at the year-ending championship in 2016, the then 18-year-old Tsitsipas was the former's hitting partner.
Come 2019, they will be locking horns for one of the most prestigious titles on the tour.
Before the two square off in the grand finale at the O2 Arena in London, let's have a look at how they have fared against each other in the past.
The first-ever meeting between the Greek Tsitsipas and the Austrian Thiem was in the quarterfinals of the 2018 Qatar Open, where Thiem triumphed 7-5,6-4 in straight sets.
The current world No. 5 Thiem made it 2-0 in the H2H count by winning the round-of-64 match 6-2, 3-6, 6-3 at the 2018 Indian Wells Open.
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The first two matches were played on outdoor hard courts. In 2018, on outdoor clay at the Barcelona Open, Tsistipas clinched his first victory against fifth seed Thiem in the quarterfinals 6-3,6-2.
The highest-ranked Austrian struck back on outdoor clay at the 2018 French Open as he downed current world No. 6 Tsitsipas 6-2, 2-6, 6-4, 6-4.
Tsitsipas got the better of Thiem 6-3, 7-6(6) in the round of 32 at the 2018 Rogers Cup
Their most recent meeting was at the 2019 China Open in October, where Thiem inched ahead to a 4-2 lead by beating the sixth seed Tsitsipas 3-6, 6-4, 6-1 in the final.
This will be the first time that the two players will meet on indoor hard court.