John Millman has hammered Bernard Tomic in their all-Australian first-round encounter at the ATP Tour's Estoril Open while countryman Alexei Popyrin fell to defending champion Joao Sousa.
World No.50 Millman got the better of Tomic in a tight first set with a single break, before he steamrolled through the second set to win 6-3, 6-0 in just 52 minutes.
Teenage qualifier Popyrin was gallant in defeat to local Sousa, battling back from a set down before he succumbed 6-4, 2-6, 6-2.
The Portuguese No.1 needed two hours and 13 minutes to battle past 19-year-old Popyrin.
In other first-round results, Argentine Leonardo Mayer knocked out fifth-seeded Dusan Lajovic with a 7-6 (7-3), 6-4 while Frenchman Jeremy Chardy ousted seventh-seeded Pablo Carreno Busta 5-7, 6-1, 6-2.
American eighth seed Frances Tiafoe, last year's finalist, progressed with a 6-3, 7-5 defeat of Mikhail Kukushkin while Malek Jaziri, qualifier Alejandro Davidovich Fokina and lucky loser Pablo Cuevas also advanced to the second round.
Meanwhile, Australian players had mixed fortunes at the WTA's Morocco Open with Ajla Tomljanovic through to the second round and Daria Gavrilova bowing out.
Fourth-seeded Ajla Tomljanovic beat Frenchwoman Fiona Ferro 6-4, 6-4 but Gavrilova was dismissed by second-seeded Hsieh Su-wei 6-1, 3-6, 6-2.
Tomljanovic will meet Timea Bacsinszky in the round of 16 after the Swiss accounted for Johanna Larsson 6-3, 6-1.
World No.24 Hsieh needed an hour and 42 minutes to dispatch Gavrilova – her first win in three career meetings with the former top 20 player.
Top seed Elise Mertens booked her place in round two with a 6-3, 6-1 victory over Kirsten Flipkens.
Sixth seed Maria Sakkari of Greece defeated Serbian Olga Danilovic 6-0, 6-2 while Lara Arruabarrena saw off Russian Vera Zvonareva 7-6 (10-8), 7-5 to secure her second-round match against Hsieh.
British seventh seed Johanna Konta saved three match points as she fought back to defeat Wang Yafan 4-6, 7-6 (7-0), 6-4.
There were also first-round wins for Belgium's Ysaline Bonaventure, American Varvara Lepchenko and Polona Hercog of Slovenia.