Shanghai managed to turn a six-point deficit after the first quarter into a 10-point lead at the end of the first half, and never looked back afterwards.
The 31-year-old also became the first Chinese singles player since Li Na in 2012 to reach the fourth round at Roland-Garros.
The Bavarians signed 31-year-old Eric Maxim Choupo-Moting (Paris), Douglas Costa (Juve), Bouna Sarr (Marseille), and Marc Roca (Espanyol) spending only 19 million euros. Reports speak of 19-year-old Tiago Dantas from Benfica having joined Bayern in a late deal to join the amateur squad.
The 19-year-old Pole needed just 68 minutes to avenge her exit to the 2018 champion last year in Paris at the same stage.
Bayern stumbled and Hertha seized the chance to restore parity at 2-2 in the 72nd, after Cunha danced through the host's defence before beating goalkeeper Manuel Neuer into the top right corner.
The five-hour and eight-minute triumph, which was Schwartzman's first victory over a top-five player at a Grand Slam, set up a rematch of the Rome quarterfinals against Spaniard Rafael Nadal, who withstood a challenge from 19-year-old Jannik Sinner and pulled away to win 7-6 (4), 6-4, 6-1 in the last match of the day, which finished at 1:30 am on Wednesday.
But Wu was reluctant to highlight her own performance.
Rodrigo Ely's 74th minute header, following a free kick, gave Alaves its first win of the season at home to Athletic Club Bilbao, who again disappointed just three days after suffering a home defeat to Cadiz and has dropped to second from bottom in the table.
Nadal will face Sebastian Korda, the son of 1998 Australian Open winner Petr Korda, in the next round. The American youngster secured his first appearance in a Grand Slam round of 16 by beating fellow qualifier Pedro Martinez 6-4, 6-3, 6-1 to advance.
The South American zone's 2022 World Cup qualifiers had been scheduled to begin in late March but were postponed because of the coronavirus pandemic.
Meanwhile Barca loaned 20-year-old left back Joan Miranda to Betis, while Rafinha Alcantara was sold to Paris Saint Germain for a bargain three million euros and central defender Jean-Clair Todibo (who is not in Koeman's plans) was loaned to Benfica on a two-year deal.