World No.1 Naomi Osaka has fought from the brink of defeat to claim victory in the first round at the French Open.

The US and Australian Open champion denied 90th-ranked Slovak Anna Karolina Schmiedlova serving out the match twice as she overcame a dreadful first set for a 0-6 7-6 (7-4) 6-1 victory on Tuesday.

Osaka ran her grand slam win streak to 15 matches after titles in Melbourne and Flushing Meadows, and narrowly avoided becoming the second women’s second top seed and world No.1 in the tournament’s 94-year history to lose in the first round.

Players faced challenging conditions on the day in the form of cool temperatures and wind as the unsettled conditions ranged from drizzle to sunshine.

Osaka, not a clay-court expert in the first place, clearly struggled against Schmiedlova who raced through the opening set in just 21 minutes.

Her fate seemed sealed when she also blew a 3-0 lead in the second after a brief rain break. But Osaka then denied Schmiedlova serving out the match at 5-4 and 6-5 – with the nervous Slovak coming only within two points of victory – before locking the sets in the tiebreak.

The third set was a formality as Osaka triumphed on first match point when Schmiedlova hit a forehand wide, winning despite 38 unforced errors, while slamming 36 winners.

Osaka’s win means that German Angelique Kerber remains the only women’s top seed and top-ranked player to go out in the first round, in 2017.

Earlier, Victoria Azarenka showed signs she is rediscovering her best form after the birth of her son Leo in 2016, as the former world No.1 dumped out 2017 Roland Garros champion Jelena Ostapenko 6-4 7-6 (7-4).

World No.123 Bianca Andreescu, playing her first match since a shoulder injury in March after winning the Indian Wells title, beat Marie Bouzkova 5-7 6-4 6-4 in a contest riddled with mistakes as the pair made a combined 92 unforced errors.

Due on court later are current title holder Simona Halep and Australian No.2 Ajla Tomljanovic.