By Drazen Jorgic

RIO DE JANEIRO (Reuters) - World number one Serena Williams and second seed Angelique Kerber progressed through the first round of the Rio Olympics tennis on Sunday despite windy conditions that delayed play on most of the smaller tennis courts.

Williams won 6-4 6-2 against Australia's Daria Gavrilova, ranked 42 in the world, but she was far from her best. The 34-year-old grew increasingly frustrated as the match wore on but was rarely threatened by Gavrilova on center court.

"The conditions definitely didn’t make it easy," said Williams, the London 2012 Olympic champion and winner of 22 Grand Slams.

Germany's Kerber, who won the 2016 Australian Open, dispatched Colombia's Mariana Duque-Marino in two sets 6-3 7-5 but also struggled with wind after a long delay to her match.

London Games Olympic champion Andy Murray was the highest-ranking male player to pass the first round after a comfortable 6-3 6-2 victory against Serbia's Viktor Troicki. Top seed Novak Djokovic was due to play later in the evening against Argentina's Juan Martin Del Potro.

A ripping wind delayed the start of most tennis matches on the second day, while even those playing on the more protected Centre Court fell foul to the conditions.

"That was first time of my life that I play in (such) terrible conditions. The wind was so fast and the match become so ugly," said Thomaz Bellucci, the top-ranked Brazilian who opened on center court. "It was almost impossible."

Bellucci, ranked 55 in the world, scraped through into the second round after Germany's Dustin Brown rolled his ankle and had to retire despite leading 6-4 4-5.

Gusts of wind also caused havoc with fans as their plastic cups went flying and umbrellas at food tables had to be lowered in case they overturned.

(Reporting by Drazen Jorgic; Editing by Alison Williams and Andrew Hay)