After an impressive opening-round win earlier this week, Serena Williams was thoroughly dominant in her second-round matchup on Wednesday night at the US Open.

Williams defeated Carina Witthoeft, 6-2, 6-2, to punch her ticket to the third round -- the 18th time she's made it to that stage. 

Awaiting Serena in the third round? Her older sister, Venus, who defeated Camila Giorgi in straight sets. It will be the first time the sisters face off in a Grand Slam since the 2017 Australian Open final.

Also on the women's side, Sloane Stephens staved off a second-round elimination with a win over Anhelina Kalinina after dropping the first set. Stephens battled back to take the next set in 12 games before winning the third set with relative ease. She will play surprising wild card Victoria Azarenka in the third round.

Elsewhere, two-time major champion Garbine Muguruza couldn't stave off an upset, leting a lead slip away in a stunning loss to 202nd-ranked Czech qualifier Karolina Muchova 3-6, 6-4, 6-4.  

Elina Svitolina advanced again after a stunning first-round exit at Wimbledon, as she looks to continue toward her first Grand Slam win and build off of a career-best fourth-round appearance in 2014. Julia Gorges, meanwhile, found herself upset by Ekaterina Makarova in straight sets.

On the men's side, Andy Murray's comeback from hip surgery is slowly progressing, but his 2018 US Open bid came to an end on Wednesday at the hands of Fernando Verdasco. The No. 31 seed Verdasco took down the world's former No. 1 in four sets, beating Murray, 7-5, 2-6, 6-4, 6-4, in the second round. 

Despite clearly not being 100 percent physically, Murray was able to defeat Australian James Duckworth in the first round. His matchup with Verdasco was always going to be a tough one, but he didn't go down without a fight. Murray underwent arthroscopic hip surgery in January and has been gradually attempting to return to form in the wake of his procedure. This was his first Grand Slam event since Wimbledon last year.

Verdasco will move on to face former US Open champion Juan Martin del Potro in the third round.

Top-seeded Rafael Nadal was in dominant form in his late-night match, winning 46 of 55 first-serve points to wear down Vasek Pospisil 6-3, 6-4, 6-2. 

Here's a look at all of Wednsday's results. 

Men's results

  • No. 9 Dominic Thiem defeats Steve Johnson 6-7, 6-3, 5-7, 6-4, 6-1
  • No. 3 Juan Martin del Potro defeats Denis Kudla 6-3, 6-1, 7-6
  • No. 5 Kevin Anderson defeats Jeremy Chardy 6-2, 6-4, 6-4
  • Daniil Medvedev defeats No. 15 Stefanos Tsitsipas 6-3, 6-3, 4-6, 6-3
  • No. 11 John Isner defeats Nicolas Jarry 6-7, 6-4, 3-6, 7-6, 6-4
  • No. 20 Borna Coric defeats Roberto Carballes Baena 7-6, 6-2, 6-3
  • No. 25 Milos Raonic defeats Gilles Simon 6-3, 6-4, 6-4
  • No. 31 Fernando Verdasco defeats Andy Murray 7-5, 2-6, 6-4, 6-4
  • Stan Wawrinka defeats Ugo Humbert 7-6, 4-6, 6-3, 5-7
  • Taylor Fritz defeats Jason Kubler 6-3, 3-6, 6-3, 0-0 (retired)
  • No. 1 Rafael Nadal defeats Vasek Pospisil 6-3, 6-4, 6-2
  • Nikoloz Basilashvili defeats No. 18 Jack Sock 4-6, 6-3, 6-2, 7-6 (3)

Women's results

  • No. 3 Sloane Stephens defeats Anhelina Kalinina 4-6, 7-5, 6-2
  • No. 7 Elina Svitolina defeats Tatjana Maria 6-2, 6-3
  • Ekaterina Makarova defeat No. 9 Julia Gorges 7-6, 6-3
  • No. 8 Karolina Pliskova defeats Ana Bogdan 6-2, 6-3
  • No. 15 Elise Mertens defeats Vera Lapko 6-2, 6-0
  • No. 17 Serena Williams defeats Carina Witthoft 6-2, 6-2
  • No. 16 Venus Williams defeats Camila Giorgi 6-4, 7-5
  • No. 19 Anastasija Sevastova defeats Claire Lu 6-3, 6-1
  • No. 23 Barbora Strycova defeats Lara Arruabarrena 6-0, 6-1
  • Victoria Azarenka defeats No. 25 Daria Gavrilova 6-1, 6-2
  • Wang Qiang defeats Irina-Camelia Begu 6-3, 6-1
  • Karolina Muchova defeats No. 12 Garbine Muguruza 3-6, 6-4, 6-4