Umag - Croatian wildcard Mate Pavic upset sixth-seeded Juan Carlos Ferrero in the first round of the Croatia Open on Tuesday, beating the former champion 6-2, 6-2.
The 19-year-old Pavic saved all four break points he faced and converted four out of the six he earned.
Pavic said "my coach told me to play my game and not pay attention to the fact that is a former No 1. This win means so much."
Ferrero won Umag in 2010, defeating Potito Starace of Italy in the final for one of his 16 career singles titles.
Earlier on Tuesday, Starace beat Slovak qualifier Ivo Klec 6-3, 7-6 (8/6) to advance to the second round.
In another upset, American Wayne Odesnik beat eighth-seeded Edouard Roger-Vasselin of France 6-7 (4/7), 6-2, 7-5.
Fabio Fognini of Italy, Blaz Kavcic of Slovenia and Marco Trungelliti of Argentina also advanced.
Fognini, a semi-finalist in 2008 and 2011, defeated Karol Beck from Slovakia 6-3, 6-1, Kavcic downed Croatia's Antonio Veic 6-2, 6-2 and Trungelliti beat Paolo Lorenzi of Italy 7-5, 6-4.
Results on Tuesday from the Vegeta Croatia Open, an ATP tour event played on outdoor clay at ATP Stadium in Umag (seedings in parentheses):
Potito Starace, Italy, def. Ivo Klec, Slovakia, 6-3, 7-6 (8/6).
Blaz Kavcic, Slovenia, def. Antonio Veic, Croatia, 6-2, 6-2.
Marco Trungelliti, Argentina, def. Paolo Lorenzi, Italy, 7-5, 6-4.
Fabio Fognini, Italy, def. Karol Beck, Slovakia, 6-3, 6-1.
Mate Pavic, Croatia, def. Juan Carlos Ferrero (6), Spain, 6-2, 6-2.
Wayne Odesnik, United States, def. Edouard Roger-Vasselin (8), France, 6-7 (4/7), 6-2, 7-5.
Daniel Brands, Germany, def. Walter Trusendi, Italy, 6-1, 7-6 (10/8).
Ernests Gulbis, Latvia, def. Gorka Fraile, Spain, 6-1, 6-3.
Carlos Berlocq (5), Argentina, def. Ivan Dodig, Croatia, 6-4, 6-0.