Andy Murray breezed through the first test of his Olympic title defence against Viktor Troicki.
The London 2012 gold medalist played his first match since defeating Milos Raonic to win a second Wimbledon title a month ago, but there were no signs of rust as he eased to a 6-3 6-2 victory.
The win was Murray's 13th in a row and seventh at the Olympics, and he will look to extend the run when he faces Argentina's Juan Monaco in the second round.
Murray, who was due back on court later for his first doubles match with brother Jamie, was given Saturday off after carrying Great Britain's flag in the opening ceremony on Friday.
The heat of the first day's play had been replaced by cool, blustery conditions, with the wind so strong that play on some outside courts was delayed for more than two hours for safety reasons.
The crowds for the tennis have been disappointing so far, but Murray received an enthusiastic reception from the quarter-full stadium when he walked out.
At 35 in the world, Troicki is one of the highest-ranked unseeded players but also a man Murray had beaten in all seven of their previous meetings.
They might have faced each other three weeks ago in the Davis Cup, but both players sat out the quarterfinal, although Murray traveled to Belgrade as a supporter.
He made a nervy start, dropping serve in the opening game, but broke straight back and soon began to take control.
The huge dimensions of the court aided Murray's supreme retrieval skills, and although he was the aggressor, Troicki struggled to come up with winners.
Some trademark Murray defence helped him break for a 4-2 lead in the opening set, and two dipping forehand passes gave the crowd something to get excited about as he broke again for 2-1 in the second.
There were certainly some positive signs for Murray, who was striking the ball crisply despite the conditions and making few errors.
A run of five games in a row took him to the brink of victory, and he clinched the win on his first match point after 1 hour, 23 minutes.
The Scot's victory made it three British singles players through to the second round after wins for Kyle Edmund and Heather Watson on Saturday, while Johanna Konta was due to play her opener later on Sunday.
Murray's fellow defending singles champion, Serena Williams, was given a battle by Australia's Daria Gavrilova, but she came through 6-4 6-2.
Watson was much more impressive in her second win of the day, as she and Konta eased to a 6-2 6-1 victory over Serbian pair Jelena Jankovic and Aleksandra Krunic in the first round of the women's doubles.
Both Konta and Watson play a reasonable amount of doubles, but not normally with each other. However, they gelled well from the start and needed just 65 minutes to move through to Round 2.