Katie Boulter's run at the Mexican Open has been brought to a halt by sixth seed Lin Zhu but fellow Britons Kyle Edmund and Heather Watson are both through to the quarter-finals in Acapulco.
Boulter upset Francesca Di Lorenzo to make the second round but Zhu proved too strong in a 7-6 (2) 7-5 victory.
The world number 394 recovered from two breaks in the first set to force a tiebreak against her Chinese opponent and Zhu showed her strength in the second as she secured a second break in the set to seal the match.
Elsewhere, Edmund beat Felix Auger-Aliassime in straight sets 6-4 6-4 to go through to the third round in Acapulco.
The Briton started the match strongly, breaking in the first game to take a lead in the first set and going on to wrap it up inside 49 minutes.
In the first meeting between the two players, Edmund, ranked 44th in the world, compared to the Canadian's ranking of 19th, took the first set without having to save any break points.
Auger-Aliassime was unable to capitalise on his opportunities, winning neither of his two break points, as he lost the second set.
Watson saw off Katerina Bondarenko in straight sets 7-6 (2) 6-2, with the first set seeing eight breaks of serve and seven in the tiebreak before the world number 69 wrapped up the second set in 38 minutes to seal the match.
Nadal on track
Rafael Nadal beat Miomir Kecmanovic in straight sets to reach the quarter-finals of the Mexican Open.
The world number two saw off his 20-year-old opponent 6-2 7-5 in one hour and 35 minutes to set up a last-eight clash with Kwon Soon-woo, who stunned eighth seed Dusan Lajovic 7-6 (2) 6-0.
Nadal won the first five games of his match and, after failing to serve out the set, he immediately broke back to secure the opener.
The second set remained on serve until the eighth game, when Nadal took his second break point.
Kecmanovic, the world number 50, broke back but the 19-time grand slam champion stepped it up in the final game to break again and secure victory.
Earlier, second seed Alexander Zverev was stunned by American qualifier Tommy Paul.
The world number 66 won 6-3 6-4.
Grigor Dimitrov beat Adrian Mannarino in a final-set tie-break while Britain's Kyle Edmund saw off fourth seed Feliz Auger-Aliassime 6-4 6-4.
American duo John Isner and Taylor Fritz were also second-round winners in Acapulco while Stan Wawrinka beat Spain's Pedro Martinez 6-4 6-4.
Dubai dominance for Djokovic
At the Dubai Duty Free Championships, world number one Novak Djokovic breezed into the quarter-finals.
The Serbian dropped just four games in a 6-3 6-1 defeat of Philipp Kohlschreiber.
Second and third seeds Stefanos Tsitsipas and Gael Monfils saw off Alexander Bublik and Yasutaka Uchiyama respectively in straight sets.
Eighth seed Benoit Paire was the day's biggest casualty, losing 6-4 6-4 to fellow Frenchman Richard Gasquet, while Russian duo Andrey Rublev and Karen Khachanov both eased through in straight sets.
Britain's Dan Evans saw off Pierre-Hugues Herbert 7-5 3-6 7-6 (7) while Germany's Jan-Lennard Struff beat Nikoloz Basilashvili 6-1 6-0.
