Serena and Venus Williams stole the headlines on Day 5 at the US Open, but the family affair was just one of many highlights on the first day of third-round play. A total of 16 singles matches were contested, and the drama began long before the sisters opened the evening session in Arthur Ashe Stadium.

Here’s a look at the top stories from the top half of the men’s and women’s singles draws.

Vintage Serena powers past Venus: Showing the sort of form that fueled her to 23 career Grand Slam singles titles, Serena was untouchable in a 6-1, 6-2 victory over her older sister. She was on the front foot from start to finish as she painted the lines with power and precision, leaving Venus stranded time after time in what she called the best match she has played since her return to tennis.

play video Highlights: Rafael Nadal vs. Karen Khachanov - Round 3

Rafael Nadal digs out of danger against Karen Khachanov: An upset was brewing as Khachanov stepped up to serve for a two-set lead against the defending champion, until Nadal dug deep to turn around a second set in which he trailed 3-5. The Russian kept coming, pushing Nadal to a tiebreak in sets three and four, but both times the Spaniard was up to the challenge as the see-saw affair ended, 5-7, 7-5, 7-6, 7-6. Nadal won the third-set tiebreak, 9-7, after a mesmerizing 39-shot rally.

Sloane Stephens edges  Victoria Azarenka: The Arthur Ashe Stadium day session opened with one of the tournament's highest quality matches to date. The 6-3, 6-4 scoreline does not do justice to the closely contested clash between the two Grand Slam champions. For the entirety of the one-hour, 46-minute tussle, it was anyone’s match until an on-the-run forehand pass earned Stephens her fourth-round berth.

Milos Raonic ousts 2016 champ Stan Wawrinka: Similar to the Stephens-Azarenka match, the Raonic-Wawrinka third-rounder contained much more intrigue than the straight-sets result would indicate. The No. 25-seeded Canadian won just 11 more points than his opponent, 97 to 86, in the 7-6, 6-4, 6-3 victory to reach Round 4 at the US Open for the first time since 2014.

Kevin Anderson wins another five-setter: The big-serving South African, who won a pair of five-set marathons en route to the 2018 Wimbledon final, was able to outlast Canadian Denis Shapovalov in Louis Armstrong Stadium. While he surely would have welcomed the US Open's use of the fifth-set tiebreak, the No. 5 seed did not need to go that far as he wrapped up his third-round match, 4-6, 6-3, 6-4, 4-6, 6-4. The three-hour, 43-minute contest was the only men's match to go the distance on Day 5, though it clocked in 40 minutes shorter than Nadal's four-setter.

At the conclusion of Saturday’s Day 6 slate, both the men’s and women’s singles draws will be on to the last 16. Roger Federer will take on Nick Kyrgios in the Arthur Ashe Stadium day session for his fourth-round place, while Novak Djokovic rounds out the evening session against Richard Gasquet. Madison Keys will open play in Ashe as she continues her quest to return to the US Open final, before hard hitters Maria Sharapova and Jelena Ostapenko play out a slugfest under the lights.

Former US Open champions Angelique Kerber and Marin Cilic will grace the Louis Armstrong Stadium Stage, as will men’s No. 4 Alex Zverev.

All three doubles events – men's, women's and mixed – will also roll on with second round action across the board.