Alexei Popyrin upset fourth-seeded Daniil Medvedev 6-4, 2-6, 7-6 (4) in the second round of the Paris Masters on Wednesday in a tense match with many ups and downs.

The 25-year-old Australian player, who won his first Masters 1000 title in Montreal this summer, had lost his three previous matches against his Russian rival.

Popyrin and Medvedev combined for a total of 86 unforced errors under the roof of the Palais Omnisports.

Medvedev trailed 4-1 in the deciding set but broke back to force a tiebreaker in which Popyrin played more aggressively. Medvedev double-faulted to give Popyrin a match point and the Australian converted it at the net.

It was Medvedev's third straight opening-round loss in Paris. He has not won a title this season.

A bad call from a line umpire which forced a point to be replayed in the eighth game of the deciding set left Popyrin furious but he recovered quickly and won the replay with a superb forehand volley to erase a break point.

“Stuff like that, I'm trying to let it fire me up rather than put me down,” Popyrin said. “It was tough to take, but it definitely fired me up after that, probably woke me up a little bit, and maybe I played a bit more free.”

Also, eighth-seeded Grigor Dimitrov stayed in the race for the ATP Finals after rallying past Tomas Martin Etcheverry 6-7 (9), 6-3, 7-5.

Dimitrov, who saved all three break points he faced, is in 10th place in the race to earn a spot at next month's ATP Finals, the year-end tournament gathering the top eight players of the season. Dimitrov could qualify if the reaches the final in Paris.

“It’s tough conditions, at the end of the year it’s very tricky,” Dimitrov said. “Everyone wants to empty their tank completely. I would give a lot to be in (the Finals). I’m in a place where I am still a contender, I’m still fighting against the best players in the world, and still beating the younger guys. This gives me confidence and makes me happy.”

French wild card Arthur Rinderknech also progressed to the third round with a 7-6 (6), 7-6 (7) win over Alex Michelsen.