Paris, May 28 (IANS): Ukraine's Kateryna Kozlova has knocked out defending champion Jelena Ostapenko of Latvia 7-5, 6-3 in the first round of the French Open, a Grand Slam clay court tennis event.

Ostapenko committed an eyebrow-raising 48 unforced errors, including 13 double faults, more than double her 22 winners during the 94-minute encounter on Sunday, reports Efe.

The 20-year-old Ostapenko thus became the first French Open defending champion to be ousted in the first round since 2005, and the second in the Open Era, following Russia's Anastasia Myskina.

Making her second appearence at the Roland Garros main draw, Kozlova went ahead 2-1 in the first set as her rival struggled with her service.

A couple of games later, Ostapenko seemed to have restored order, breaking her rival's serve for 4-4.

Both players, then, traded service breaks, but Kozlova got the decisive one to take a 6-5 advantage and held her next serve to seal the first set.

Neither player could hold her first two service games in the second set, and they wound up tied at 3-3.

It was then that Kozlova won three consecutive games to earn her third win over the Latvian player in as many career matches.

In her first second-round appearance at Roland Garros, Kozlova will play either Katerina Siniakova of the Czech Republic or Victoria Azarenka of Belarus.