Paris (AFP) - Top seed Naomi Osaka admitted that a 10-minute toilet break by Victoria Azarenka helped her to a second successive Roland Garros great escape on Thursday.
The Japanese star, bidding to add the French Open to her US and Australian Open titles, battled back from a set and a break down to defeat Azarenka 4-6, 7-5, 6-3.
Both players left Court Suzanne Lenglen before the start of the third set for toilet breaks.
Osaka returned quickly but former world number one and two-time major winner Azarenka disappeared for close on to 11 minutes.
While 21-year-old Osaka bided her time, many observers wondered if the lengthy delay was a deliberate act of gamesmanship.
If it was, it backfired.
"When I went to the bathroom to change, I was freaking out, because I didn't want to get a code violation," explained Osaka.
"So I was, like, rushing and stuff. And then I came back and saw that she wasn't back. That kind of just relaxed me.
"I was in such a rush changing, my hands were shaking during that entire time. So when I came back and saw she wasn't back, I just had a little bit of time to calm down and think about what I really wanted to do during the set. So, for me, I was fine."
Osaka had been two points from defeat in her opener against Anna Karolina Schmiedlova.
Against former number one and two-time major winner Azarenka she was staring down the barrel yet again at 2-4 down in the second set.
However, she held her nerve, despite squandering two match points, to secure a place in the third round and a clash against Katerina Siniakova of the Czech Republic.
"The first round obviously was really tough, and I think the first round is tough for everyone," added Osaka.
"And this round, I was playing Azarenka, which is not the best combination.
"But I feel like I have to win. I acknowledge that's kind of a toxic trait, but, like, it's gotten me this far."
Osaka finished the two-hour 50-minute encounter on Thursday with 52 winners and 43 unforced errors.
She becomes the first top seed to win her two opening matches at Roland Garros after losing the first set since Lindsay Davenport in 2005.
Azarenka, now at 43 in the world, claimed the 40-minute first set having stretched out to a 5-1 lead on the back of two breaks of serve.
Osaka was undone by 15 unforced errors.
The Japanese star appeared doomed when she slipped 4-2 down in the second set having failed to convert three break points in the fourth game.
But she rallied to level at 4-4 after a 10-minute eighth game, secured on an Azarenka double fault.
The Belarusian, who had knocked out 2017 champion Jelena Ostapenko in the first round, then saved three set points in the 12th game before Osaka levelled the contest with a pinpoint, down the line winner.
After an 85-minute set, Azarenka took her lengthy break before squandering three break points in the first game of the decider.
Osaka made her pay, breaking twice for a 5-1 lead.
However, in a rollercoaster of a match, Azarenka cut the deficit to 5-3, saving two match points in the process.
"I didn't push enough through so I have to learn from that but I have to take positives from the match," said 29-year-old Azarenka.
"She deserves to be where she is -- she is very powerful and explosive."
Siniakova, the world number 42, also endured a marathon win, putting out Greek 29th seed Maria Sakkari 7-6 (7/5), 6-7 (8/10), 6-3 in a three-hour 10-minute duel.