Marin Cilic claimed a much-needed win in the Citi Open second round, while Jo-Wilfried Tsonga caused an upset on Tuesday.
Cilic, yet to hit top form this year, battled past Marius Copil 7-6 (7-4) 7-6 (7-4) to reach the last 16 at the ATP 500 event in Washington.
The Croatian sixth seed and 2014 US Open champion improved to just a 12-10 win-loss record this year thanks to the hard-fought victory.
The only seed to fall on Tuesday was Karen Khachanov, who went down to Tsonga.
Tsonga served 13 aces in a 6-4 2-6 7-5 victory over Khachanov, the second seed losing to the Frenchman for the third time in as many meetings.
Daniil Medvedev, Kyle Edmund and Frances Tiafoe joined Cilic and Tsonga in the third round.
Medvedev eased past wildcard Bjorn Fratangelo 6-3 6-4, Edmund crushed Lloyd Harris 6-1 6-4 and Tiafoe was too good for Alexander Bublik 6-1 7-6 (7-5).
Meanwhile, Jack Sock's wait for a first singles win of the year continues after losing 7-5 6-3 to Jordan Thompson in the first round.
Nick Kyrgios sent down 15 aces on his way to a 7-5 6-4 win over qualifier Thai-Son Kwiatkowski, Reilly Opelka edged Christopher Eubanks 6-4 7-6 (7-3) and Yoshihito Nishioka was untroubled by Dan Evans in a 6-4 6-1 victory.
Peter Gojowczyk and Miomir Kecmanovic also advanced after wins over Andrey Rublev and Alexei Popyrin respectively.
Fucsovics out as seeds are sent packing at Generali Open
Marton Fucsovics was among three seeded players to exit the Generali Open in the first round as he went down to Albert Ramos-Vinolas in three sets.
Fifth seed Fucsovics squandered a one-set lead to lose 6-7 (6-8) 6-4 6-4 to Ramos-Vinolas on Tuesday in a match that lasted over three hours.
Ramos-Vinolas won his first title of the season in Gstaad last weekend and will face compatriot Jaume Munar, who beat Thomas Fabbiano 7-6 (9-7) 1-6 6-1, in round two.
There were also wins for Jozef Kovalik and Austrian wildcard Sebastian Ofner, who will face top seed and 2019 French Open runner-up Dominic Thiem next.
Leonardo Mayer and Pablo Carreno Busta – seeded sixth and eighth respectively – followed Fucsovics in bowing out.
Hamburg Open semi-finalist Carreno Busta came unstuck 6-1 3-6 6-1 against Norwegian youngster Casper Ruud, while Mayer went down 3-6 6-3 6-2 to Pablo Andujar.
Kitzbuhel resident Philipp Kohlschreiber – who won the Generali Open in 2015 and 2017 – ended a five-match losing streak by overcoming Richard Gasquet 6-3 6-2.
Dimitrov hangs on
Grigor Dimitrov battled to a hard-fought win in the Los Cabos Open first round, while Taylor Fritz was untroubled on Tuesday.
Dimitrov, who has fallen out of the world's top 50 after a tough first half of the year, got past Steve Johnson 7-6 (7-4), 4-6, 7-6 (7-5) at the ATP 250 tournament.
The Bulgarian served 12 double faults but still managed to edge through for his first victory since the French Open.
Fritz, coming off a run to the final in Atlanta, disposed of German Dominik Koepfer 6-3, 6-4 in just an hour.
The American fifth seed managed to break once in each set in what was a routine outing.
Radu Albot, the seventh seed, also managed to get through courtesy of a 7-5, 2-6, 6-0 win over Janko Tipsarevic.
The only seed to depart was Cristian Garin, who went down to Juan Ignacio Londero 3-6, 6-2, 6-3.
Tennys Sandgren was thrashed 6-2, 6-0 by Taro Daniel, Cameron Norrie got past Gregoire Barrere 7-6 (7-5), 6-0 and qualifier Kwon Soon-woo easily beat Cedrik-Marcel Stebe 6-2, 6-1.