Alexei Popyrin has made a good start to the Srpska Open, defeating Dutch fifth-seed Tallon Griekspoor.
The only Australian competing in the ATP 250 event in in Banja Luka, Bosnia-Herzegovina, 81-ranked Popyrin beat the world No.34 7-6 (7-4) 7-6 (7-4).
Popyrin now plays Slovakian Alex Molcan, 73rd in the world, who came back from losing the first set to defeat Japan's Taro Daniel 3-6 7-5 6-1.
Veteran Stan Wawrinka, now 38, was denied a second round meeting with old foe Novak Djokovic, who he twice defeated in grand slam finals, when he lost to French teenager Luca Van Assche 1-6, 7-6 (7-4) 6-4. The 18-year-old now faces No.1 seed Djokovic for the first time.
Australian interest in another ATP 250 event in Munich is over after Jordan Thompson lost to qualifier Flavio Cobolli in the opening round. On his first outing in the European clay-court swing this year Thompson was beaten 7-5 6-1 by the 208-ranked, 20-year-old Italian.
Two Aussies are in the draw at the ATP 500 Barcelona Open. Jason Kubler plays his first round match against wild card Daniel Rincon on Tuesday (early Wednesday AEST) while national No.1 Alex de Minaur has been given a bye into the second round.
Monday's play in Catalonia brought victories for young American Ben Shelton, Finn Emil Ruusuvuori over Alexander Bublik, Tomas Martin Etcheverry of Argentina and Nuno Borges of Portugal. Borges will face defending champion Carlos Alcaraz in the next round.
