Caroline Wozniacki has called on Miami Open organizers to act after members of her family were subject to death threats during her defeat to Monica Puig on Friday.

Australian Open champion Wozniacki was seeded second for the WTA Premier Mandatory event and was making her first appearance after a bye in the first round.

The Dane was unable to make a winning start against the Olympic champion, though, as Puig battled back from a first-set bagel to prevail 0-6 6-4 6-4.

And Wozniacki has made allegations of abuse from the crowd, aimed at herself, her parents and her fiance David Lee's young niece and nephew.

The 27-year-old revealed the details of the verbal attacks in a Twitter post, in which she called for something to be done by tournament officials.

"Last night I lost a tough match to a great opponent and friend Monica Puig at the Miami Open," she wrote. "I am fully aware that tennis is a game of wins and losses."

"However, during the match last night people in the crowd threatened my family, wished death upon my mom and dad, called me names that I can't repeat here and told my fiance's niece and nephew (who are 10 years old) to sit down and shut the f*ck up, meanwhile security and staff did nothing to prevent this and even accepted this to take place."

"While I always encourage fans to cheer for their favourite player, and I thrive on a challenging atmosphere, when certain lines are crossed, it makes tennis miserable for both competitors."

"I hope the Miami Open chooses to take this seriously because it's a horrible example to set for the next generation of tennis players and fans. I wish Monica all the best for the rest of the tournament."

Puig will face Maria Sakkari in the third round on Sunday.