Marinko Matosevic upset second seed John Isner and the local fans at the Delray Beach ATP event on Tuesday in a mixed day for the five Australians in first-round action.
Bernard Tomic and Thanasi Kokkinakis also scored first-round victories at the hard-court tournament in Florida, but a typically powerful serving display from fellow Australian Sam Groth wasn’t enough and qualifier John-Patrick Smith fell to top seed Kevin Anderson.
Matosevic’s win over the big-serving world No.19 Isner, who lives in the Florida city of Tampa, will provide a big boost after a slow start to his season.
Matosevic’s only victory in 2015 was in the first round of the Australian Open in between early exits in Brisbane, Sydney and Memphis.
Isner, who won all three prior meetings against Matosevic last year, surrendered a service break in each set while squandering all three of his own chances in the 75-minute encounter.
Tomic, who reached the quarter-finals of the Memphis Open last week, outclassed Tunisia’s Malek Jaziri 6-3 6-3 while Kokkinakis was too strong for Serbian Filip Krajinovic in a 6-2 6-3 victory.
Groth slammed down 15 aces but went down 6-7 (6-8) 7-6 (7-5) 6-4 to Taiwan’s Yen-Hsun Lu.
South African Anderson, who lost to Kei Nishikori in the Memphis final, prevailed 6-3 6-3 over Smith.
Meanwhile, US sixth seed Sam Querrey was forced to withdraw with a sore back while leading his first-round match 6-3 1-2 against Colombia’s Alejandro Gonzalez.
“I had a sudden movement at the net and kind of jerked my back a little bit,” Querrey said.
“It’s an injury that I felt before, but never on a specific motion like this. My lower back just kind of tightened up and I can’t really move it in any direction.”
Gonzalez will next face American Donald Young, whose hot streak of form – he reached the semi-finals in Memphis – continued with a 7-5 7-5 defeat of Croatia’s Ivan Dodig.
French fifth seed Adrian Mannarino defeated US qualifier Eric Quigley 6-4 6-4 while US seventh seed Steve Johnson advanced 6-3 4-1 when Kazakstan’s Mikhail Kukushkin retired due to illness and Serbian eighth seed Viktor Troicki outlasted France’s Stephane Robert 6-7 (3-7) 7-5 6-1.
