Serena Williams' quest for a 24th grand slam singles title continued while men's second seed Dominic Thiem proved why he is the main competition to Novak Djokovic.
Australian Open champion Sofia Kenin also progressed but there was a top-10 seed on the men's side who was defeated.
Here, the PA news agency looks back at day six at the US Open.
Picture of the day
Shock of the day
Canadian Vasek Pospisil began the tournament by helping Novak Djokovic set up the Professional Tennis Players Association but off-court distractions appear to have galvanised him, and the 30-year-old reached the fourth round here for the first time with a 7-5 2-6 4-6 6-3 6-2 upset of eighth seed Roberto Bautista Agut.
Shot of the day
Marton Fucsovics may have gone down in straight sets to Frances Tiafoe, but he will always have this round-the-net winner after a cat-and-mouse rally to remember.
Rally of the day
Any rally that has a tweener followed by a winner at the net needs highlighting and Felix Auger-Aliassime was the provider during his routine win over Corentin Moutet.
Supporter of the day
Giovanni Bartocci is the only contender for this as he turned up to the Flushing Meadows grounds with a megaphone to show his support for Matteo Berrettini. The Italian ate at Bartocci's restaurant every night during his run to last year's semi-final and the pair became close. The restaurant has since sadly burned down, but Berrettini is still feeling the love. The number six seed, who beat Casper Ruud in straight sets, said: "I'm really looking forward to try to help him maybe a little bit. I don't know what we can do. He's struggling. I don't know if he's going to come back in Italy, but I'm really thankful that he's here. He's enjoying a little bit different this year. But he's a nice guy."
Stat of the day
Canada Day was in July, but three men have given their country the tennis version in September as Denis Shapovalov, Vasek Pospisil and Felix Auger-Aliassime made it through to the fourth round.
Quote of the day
Fallen seeds
Women: Madison Keys (7), Donna Vekic (18), Amanda Anisimova (22), Sloane Stephens (26),
Men: Roberto Bautista Agut (8), Karan Khachanov (11), Casper Ruud (30), Marin Cilic (31)
Up next
Novak Djokovic will look to make it 27 wins in a row when he takes on Spaniard Pablo Carreno Busta in the fourth round, while women's fourth seed Naomi Osaka has the headline spot on Arthur Ashe against Anett Kontaveit. Former champion Angelique Kerber and sixth seed Petra Kvitova are also in action and Shapavolov's clash with David Goffin looks a mouth-watering one.
