This season Djokovic has a compiled 40-3 match record. It was a little bit shaky from both of us in the beginning from one [point] of view, but from the other [point] of view, I think there were some unbelievable points.
"It's going to be another tough one but playing like this I am confident that I can have my chances in the tournament", Nadal, twice a runner-up in London, said. "Hoping I can end my season in the best possible way".
But Thiem hit straight back, his backhand down the line again proving the key weapon in his arsenal against the great Spaniard. He also has never lost to Schwartzman in six matches.
The world No. 2 has won 86 titles but just one of those has come on an indoor hard court.
The Austrian needed three tie-breaks to take a four-set victory over Nadal at the Australian Open in January and Tuesday's clash in London was similarly played on a knife-edge.
But no matter the size of the Argentine's heart, this looked a step too far.
The quality of the rallies in the first set would have graced a final in front of a sell-out crowd with neither player taking a backward step. But he was perhaps not prepared for how quickly Schwartzman settled in.
This time round, Thiem held his nerve only dropping serve once as he converted his second match point during the tie-break to win it 4-7 and claim the second set. However, that has been changed following a best-of-3 scoreline.
Schwartzman broke Djokovic for a 2-1 lead in the first set, but the 28-year-old Argentine immediately gave it back as he struggled with his first serve. The Russian was overwhelmed in the lopsided 6-1 first set.
Schwartzman seemed unable to break his opponent's rhythm, drawn into metronomic exchanges that were simply flawless from the Djokovic side.
The top-ranked Djokovic smothered Schwartzman after conceding an early break and, despite no fans inside the 20,000-capacity O2 Arena, he gestured to each section as if to say thanks. Schwartzman's body language, a shrug of the shoulders to his team as he took the baseline to receive, spoke volumes.
The Serbian admitted he had started slowly but said he was pleased with his game as the match wore on. At an average age of 61, said the current world no. 1, people can not be expected to remain glued to their television screens while following an unnecessarily long match.
With no room for human error, players have also been denied the chance for Hawkeye challenges - a popular feature for tennis since it was introduced at the 2006 U.S. Open. "As we have a day off between games, we must keep that fundamental part of the history of our sport".
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