World number three Rafael Nadal outlasted Jack Sock in a three-hour epic to progress through to the third round at the Citi Open in Washington D.C. on Wednesday.

The 20-time Grand Slam winner needed a third-set tiebreaker to beat American wildcard Sock 6-2 4-6 7-6 (7-1).

Sock, who is currently ranked 192nd in the world, stormed back into the match with an early break in the second set after the Spaniard cruised in the first.

In a three-hour-and-a-four-minute match which saw only five breaks, Nadal got the edge winning more on his second serve, while he produced some vintage winners too.

Nadal goes through to the third round where he will face 14th seed Lloyd Harris, who progresses after a walkover with Tennys Sandgren retiring mid-match.

Third seed and world number 18 Alex De Minaur was bundled out by world number 81 Steve Johnson 6-7 (5-7) 6-4 6-2.

Fourth seed Grigor Dimitrov also was dumped out with a 6-2 7-6 (7-4) defeat to Belarussian world number 65 Ilya Ivashka.

Sixth seed Dan Evans went out in straight sets to 20-year-old American Brandon Nakashima 7-6 (7-1) 6-0 while 10th seed Taylor Fritz also bowed out to Denis Kudla 6-4 6-2.

Former winner Kei Nishikori knocked off ninth seed Alexander Bublik 6-2 7-5, while 13th seed Benoit Paire lost in three sets to Mackenzie McDonald.

Fifth seed Jannik Sinner got through in straight sets against Emil Ruusuvuori, along with eighth seed Reilly Opelka and 11th seed John Millman.

Second seed Felix Auger-Aliassime survived after an early scare against Andreas Seppi to progress to the third round at the Citi Open in Washington D.C. on Tuesday.

The Canadian world number 15 won 2-6 6-2 6-2 in just under two hours over the 37-year-old Italian.

Seppi had beaten Auger-Aliassime in the opening round at the French Open in June.

Auger-Aliassime this time hit 25 winners, including nine aces, overcoming a slow start where he was broken twice inside the opening six games to win in three sets.

Youngster Jenson Brooksby continued his bright start in Washington D.C. with a 7-6 (7-4) 7-5 win over fellow American Francis Tiafoe.

Australian Nick Kyrgios was bundled out by Mackenzie McDonald 6-4 6-4, while 12th seed Sebastian Korda eased past Vasek Pospisil 7-5 6-4 in the second round.

Seventh seed Cameron Norrie also triumphed in straight sets over Marcos Giron 6-4 6-3, while emerging star Brandon Nakashima celebrated his 20th birthday with a 6-3 6-3 victory over Alexei Popyrin.

Denis Kudla beat Feliciano Lopez to set up a second round date with 10th seed Taylor Fritz, while Tennys Sandgren will meet 14th seed Lloyd Harris after beating James Duckworth in three sets.

Finland's Emil Ruusuvuori beat India's Prajnesh Gunneswaran 2-6 6-1 6-1 and will take on fifth seed Jannik Sinner in the second round.

Young American Jenson Brooksby claimed some revenge for last month's Hall of Fame Open final defeat to Kevin Anderson by beating the South African 7-6 (7-4) 6-3 in the Citi Open first round on Monday.

Brooksby, who received a wildcard for the draw, triumphed in one hour and 49 mnutes against the former world number five.

The 20-year-old American saved a set point at 5-6 in the first set, before winning in a tiebreaker off the back of winning six consecutive points having trailed 1-4.

Former City Open finalist Anderson, who sent down 10-1 aces, had defeated Brooksby to win the Hall of Fame Open last month.

World number 130 Brooksby, who had started the season outside the top 300, claimed the crucial break in the eighth game of the second set.

Brooksby advances to take on American Francis Tiafoe, fresh from competing at Tokyo 2020, as numerous big names enter the draw for the second round.

Kei Nishikori, who won in Washington in 2015, got past American Sam Querrey 6-4 6-3 to set up a second round meeting with Kazakhstani ninth seed Alexander Bublik.

American Jack Sock will take on top seed Rafael Nadal in the second round after he got past Yoshihito Nishioka in a walkover 6-7 (3-7) 4-0.

Former top 20 player Andreas Seppi triumphed in three sets against Yasutaka Uchiyama while Canadian tour veteran Vasek Pospisil got past Emilio Gomez in three.

Ilya Ivashka, Marcos Giron, Ricardas Berankas and Daniel Galan were the other first round winners on Monday.