Two weeks past his 21st birthday, Khachanov became the youngest man to reach the fourth round here since 2009, beating 21st-seeded John Isner - the last American man in the tournament - 7-6 (1), 6-3, 6-7 (5), 7-6 (3).
Defending champions Novak Djokovic and Garbine Muguruza were also in action later.
On a more serious note, Djokovic said he was pleased with his form after coming through some hard times since completing a career Grand Slam at Roland Garros a year ago.
To add another upbeat dimension to proceedings in Paris, the French crowd was guaranteed at least one home player in the quarter-finals as Caroline Garcia more than fulfilled her seeding to reach the fourth round-her best run at any Major thus far-and would meet the unseeded Alize Cornet, who put out both No20 seed Barbora Strycova and No9 seed Radwanska.
'March for Truth' calls for investigation into Trump, Russia
The rally's name was a reference to Trump's remarks this week announcing his decision to pull out of the Paris climate accord. For many in the crowd, this was just the latest in a string of anti-Trump protests to unfold on the National Mall.
In the absence of Serena Williams and Maria Sharapova, Mladenovic has been tipped as one of the favourites for the tournament after reaching finals in Stuttgart and Madrid, but her path to the title remains littered with risky opponents. Spain's Rafael Nadal smiles after defeating Georgia's Nikoloz Basilashvili during their third round match of the French Open tennis tournament at the Roland Garros stadium, Friday, June 2, 2017 in Paris.
It was a slow start for the Spanish world number five, but she eventually worked her way into the contest, growing in confidence as the game progressed to set up a third-round match against Yulia Putintseva.
Mladenovic broke down in tears during her post-match speech to the crowd, telling her supporters: "The courage and the force you give me is just unimaginable". This time, she would need two hours to complete her 6-1, 3-6, 6-3 win and it took her to her first Roland Garros quarter-final.
Next up against Nadal is 20th-seeded Pablo Carreno Busta, who knocked off No. 5 Milos Raonic 4-6, 7-6 (2), 6-7 (6), 6-4, 8-6.
Gregg Allman Funeral Set For Saturday
Allman will be buried at Macon's Rose Hill Cemetery, next to his brother Duane and late Allman Brothers band mate Berry Oakley . I guess in the late '90s, we were playing a date together and I got to meet him finally and just really liked him as a person.
The 24-year-old Mladenovic never had been past the third round at her home major - and has never made it beyond the quarterfinals at any other. The last woman representing France to win the country's Grand Slam tournament was Mary Pierce in 2000. She next takes on 2012 runner-up Sara Errani.
Venus Williams will turn 37 later this month, yet still played here as seeded No10.
The 31-year-old Nadal is seeking his 10th French Open title and 15th Grand Slam title. Bacsinszky showed great fight after dropping the first set, and she lost just three games in the two sets she won to advance. Mladenovic often played to the fans, waving her arms to ask for more noise. His last major came at Roland Garros in 2014. In the victory, Mladenovic won 70 percent of her first serve points and 43 percent of her second serve points.
It was the second year in a row the Swiss had beaten Williams in the fourth round.
Rafael Nadal Demolishes Robin Haase in Straight Sets
French Open favourite Rafael Nadal demolishes Robin Haase 6-1, 6-4, 6-3 and moved into the third round of the French Open . The two-time Wimbledon champion was injured when a burglar stuck a knife through her playing hand late previous year .