The Latest on the French Open (all times local):
Two-time Wimbledon champion Petra Kvitova is having trouble on Court Philippe Chatrier.
The 10th-seeded Czech looked in control after breaking Danka Kovinic twice to win the first set 6-2 but dropped the second 6-4.
Kovinic has never gone beyond the second round at any Grand Slam tournament while Kvitova's best result at the French Open is a semifinalist spot back in 2012.
Earlier, 24th-seeded Anastasia Pavlyuchenkova became the first player to advance to the second round with a 6-2, 6-0 win over Sara Sorribes Tormo.
Despite rain much of the morning, the French Open has started.
The forecast calls for showers on Sunday, but a break in the weather allowed two-time Wimbledon champion Petra Kvitova onto Court Philippe Chatrier to face 59th-ranked Danka Kovinic of Montenegro in a first-round match.
Other players scheduled to play on Day 1 of the clay-court tournament include 2014 U.S. Open runner-up Kei Nishikori, eighth-seeded Milos Raonic, and 2015 Wimbledon finalist Garbine Muguruza.
The French Open is the only Grand Slam tournament that begins on a Sunday.
About six months after the deadly attacks in Paris, heightened security at Roland Garros was noticeable, including extra bag checks and patdowns that led to longer-than-usual waits at the entrance gates.