Tsitsipas retired injured from his second-round match against Australian Alexei Popyrin with what appeared to be a right arm problem.
Ons Jabeur will become the first Arab player to crack the top 10 of the world rankings after reaching the Indian Wells semi-finals.
World number two Rafael Nadal captured his first ATP Tour title of 2020, easily defeating unseeded Taylor Fritz in straight sets, 6-3, 6-2, in the final of the Mexico Open on Saturday.
Rafa Nadal has withdrawn from next week's season-opening exhibition event in Abu Dhabi due to ongoing fitness problems, the world number one has said.
Players will have an additional five seconds between points at next year's Australian Open but time-wasters will have nowhere to hide thanks to the introduction of shot-clocks.
Grigor Dimitrov claimed the biggest title of his career and sent out a huge statement of intent as the stylish Bulgarian beat David Goffin to win the ATP Finals.
Roger Federer went through round-robin play at the ATP Finals undefeated for the 10th time.
Rafael Nadal's unforgettable season came to a painful end when he withdrew from the ATP Finals.
World number one Rafa Nadal is confident he will be "100 percent fit" at the ATP Finals event in London as he continues to recover from a knee injury.
A hoped-for fight to the finish for the year-end number one ranking at next month's ATP World Tour Finals in London will likely be a coronation for Rafa Nadal.
Line judges face an uncertain future after the ATP announced that they will be replaced by "electronic line calls" at this year's inaugural Next Gen Finals in Milan.
Egyptian tennis player Mohamed Safwat, who is ranked 211th in the world, lost in the quarter-finals of the Shanghai Challenger Tournament, held in Shanghai, China.