Seventh seed Mikhail Youzhny beat Johan Nikles 6-3 6-2 to reach the second round of the J. Safra Sarasin Swiss Open in Gstaad.
The veteran Russian, winner of the tournament in 2013, saved three break points as the world number 66 saw off a spirited challenge from the 19-year-old home player, who was making his ATP World Tour debut.
Elsewhere, Swede Elias Ymer progressed past Daniel Brands, coming from behind to beat the German 2-6 7-6 (9/7) 7-5 in just over two hours for a first World Tour win in more than a year.
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Czech qualifier Jan Mertl, 34, beat Swiss Yann Marti 6-4 6-7 (5-7) 6-2 and will next play top seed Feliciano Lopez, while Thiago Monteiro of Brazil defeated home wildcard Antoine Bellier 6-3 7-5 to secure a second-round match against second seed Gilles Simon.
There was an upset in the opening round of the Generali Open Kitzbuhel in Austria, where seventh seed Inigo Cervantes of Spain crashed out 6-4 6-4 against Spanish qualifier Daniel Gimeno-Traver, ranked 131 in the world.
Russia's Karen Khachanov booked a second-round match against second seed Philipp Kohlschreiber after he beat Italian Filippo Volandri 6-2 6-4.
At the Konzum Croatia Open Umag, Serbian qualifier Nikola Cacic recovered from losing the first set to defeat British number three Aljaz Bedene 5-7 6-4 6-4.
Cacic, ranked 761 in the world, will next play French third seed Jeremy Chardy, who was given a bye straight into the last 16.
The other main-draw match saw Croatian wildcard Nikola Mektic defeated 7-5 6-2 by Leonardo Mayer of Argentina, who will go on to play Joao Sousa, the second seed, in round two.
John Millman reeled off the last seven games of the match to beat local hope Denis Kudla 7-5 6-0 in the first round of the Citi Open in Washington.
Fellow Australians James Duckworth and Jordan Thompson also advanced, with Duckworth overcoming America's Tim Smyczek 7-5 6-1 and Thompson getting the better of Victor Estrella Burgos 6-3 6-2.
Bjorn Fratangelo won an all-American battle against Alex Kuznetsov 4-6 6-2 6-4, while Great Britain's Dan Evans saw off Germany's Benjamin Becker 6-2 6-1.
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