Defending champion Iga Swiatek reached the quarter-finals of the French Open on Monday with a 6-3, 6-4 victory over Ukrainian teenager Marta Kostyuk. The eighth seed from Poland has won 22 straight sets at Roland Garros and will take on Greek world number 18 Maria Sakkari for a place in the last four. Sakkari knocked out last year's French Open runner-up Sofia Kenin earlier in the day, leaving Swiatek as the highest-seeded player remaining in the draw. Swiatek, 20, is aiming to become the first woman to defend the title in Paris since Justine Henin won the tournament three times in a row from 2005 to 2007. She extended her winning streak to 10 matches, having captured the Italian Open title in Rome last month. The 18-year-old Kostyuk, ranked 81, was making her first appearance in the last 16 of a major. mw/lp