Rus, the 94th-ranked player on the WTA rankings, won her first game in Paris since 2012 when Angelique Kerber was knocked out in last year's first round. Osorio, meanwhile, made it to the second round of the French Open for the past three years and promised to be a formidable opponent for the 34-year-old Rus.
Both players opened the game with a few lapses of focus as the first four games all ended in breaks. Rus erased five break points in the sixth game to stay in the race. The first set eventually fell Osorio's way after a late break earned her a set win: 6-4.
Rus fought back with a vengeance and overwhelmed Osorio, breaking the Colombian twice en route to a convincing 6-2 set win.
With one set each, a deciding third set had to bring a winner. Set dealt the first blow again and broke Osorio to go up 2-1. Rus eventually won a hard-fought set after four consecutive breaks became too much for Osorio. Rus pulled off the upset over a player placed 43 spots above her and booked a place in the second round for the second-straight year.
Rus will meet the winner of the matchup between Claura Tauson and Magda Linette in the second round.
View all the match statistics on Flashscore.
