PARIS, France - For the second straight match at the French Open, World No.1 Naomi Osaka was down, but not out.

In a second-round clash that lived up to its billing, Osaka rallied from a set and a break down to defeat Victoria Azarenka in nearly three, dramatic hours on Court Suzanne-Lenglen on Thursday, 4-6, 7-5, 6-3.

Azarenka, bidding for her first win over a reigning World No.1 in three years and first-ever at a Grand Slam, sprinted out to a 4-0 lead to start the match before Osaka found a foothold, and ultimately built a 6-4, 4-2 lead as she sought the victory.

"I feel like I didn't dip at all during this match, and she was just playing so well. I was just waiting for her to get a little bit tired," Osaka said after the match.

"I think she did towards the end of the second set and the third set, so that's when I just tried to really accelerate on how fast I was sort of winning the points.

"After a certain point, I don't even look at the score. I just try to take it point by point. I have this mindset that I feel like I can win if it gets down to the wire. If I have to break a person, I feel like I have the ability to do that."

The Belarusian last reached the third round in Paris in 2015, her deepest showing since reaching the semifinals in 2013, and looked to close in on a spot in the round of 32.

She had a break point for a 5-2 advantage in the second set, and two game points on her serve in the eighth game to lead 5-3, but could not get over the line in a match which ultimately lasted two hours and 50 minutes. 

As It Happened: Osaka roars to Azarenka comeback win in Paris

Osaka - who was two points away from defeat in her first-round match against Anna Karolina Schmiedlova - battled back valiantly, raising her level with her back against the wall to seal five of the last six games in set two to take the match the distance. 

"I think this match was equal parts mental and physical. Maybe more mental," Osaka added, 

"Yhe first set was, I got rolled. I made a little bit of a comeback in the end of the first set, but technically, she kind of killed me in the first set, and I just kept trying to find a way to stay positive."

After both players left the court prior to a tense final set, it was Osaka who quickly moved into the ascendancy.

The top seed staved off three break points in the opening game, and after the pair traded service holds, she ripped off four straight games to seal a 5-1 advantage.

Never beaten, Azarenka saved a match point to secure back-to-back games and went down swinging, earning herself a break point in what proved to be the match's final game. 

"I really played the right spots. I was playing aggressive. I was doing everything that I was supposed to do, and especially moving well and pushing her back," Azarenka said in defeat.

"I believe I didn't take some of my chances where I had, but I felt that the margin of opportunity was very little for both of us today. I didn't push enough through, which is something that I need to learn from.

"She has obviously a lot of confidence playing right now, so in those moments, she's been a lot in those situations where those margins are really small.

"I need to have some more of those experiences, but I'm pretty positive that I can take a lot of things out of this match and turn them into positive for my next tournaments."

However, big serving came to Osaka's rescue in the end, as she hammered down consecutive unreturnable deliveries en route to finally closing out the match.