Michelle Obama pays tribute to tennis icon Billie Jean King in a surprise speech at the US Open

Billie Jean King fought against gender discrimination throughout her career. She constantly raised her voice against prejudice and led through example in this struggle. Former first lady Michelle Obama recently paid tribute to the icon in a heartfelt speech on the 50th anniversary of the U.S. Open becoming the first sporting event to offer equal prize money to female and male competitors. The unexpected tribute took place on the opening night of the tennis championship for King's achievement in fighting for equal pay for women in tennis.

The event was also attended by former President Barack Obama who has been outspoken about how King and her work has impacted his style of parenting. The event reminisced all the bold steps King took in her illustrious career that led the women's movement in sports, reports PEOPLE.

Michelle, as seen in a clip obtained by Sky Sports, mentions how King has always stood as an inspiration for people around her. "Billie Jean teaches us that when things lie in the balance, we all have a choice to make," the mother-of-two said. "We can either wait around and accept what we’re given. We can sit silently and hope someone else fights our battles. Or we can make our own stand."

Though King has garnered more than 30 titles to her name over the course of her career, the landmark moment of her career was when she beat Bobby Riggs in a heavily publicized "Battle of the Sexes" match. The win was huge for women in tennis as it was the first time a female player received the same amount a man would get for winning a match - $25,000. It also sheds light on the importance of women's sports, and how female players can perform on equal footing with their male counterparts.

Before the match, King displayed her distaste towards the gender disparity that existed between male and female players in tennis by refusing to play again. This reaction came when she was awarded $10,000; $15,000 less than what a man would get after winning the US Open. She spent an entire year rallying women players to demand equal pay and her cause received significant attention when she won her match against Riggs, which turned out to be the largest viewed event in tennis history. Her efforts proved successful and in the following year's US Open, men and women were given equal compensation.

It took three more decades for all Grand Slam events to follow suit and provide men and women with the same compensation. In her speech, Michelle displayed gratefulness for this monumental change but warned that there are still many more hills to climb. "Let us remember all of this is far bigger than a champion’s paycheck — this is about how women are seen and valued in this world," she said. "Sadly, we have seen how quickly progress like this can be taken away if we are not mindful and vigilant."

Taking to the stage after the former first lady’s tribute, King asked people to stand up for themselves and not expect others to fight their battles. She added that individuals owe it to their future generations to persevere through the struggles. "We can use whatever platforms we have to speak out and fight to protect the progress we’ve made, and level the playing field for all of our daughters and their daughters," she said.

King also encouraged people to speak up for themselves by sharing a quote from Coretta Scott King: "'Struggle is a never-ending process. Freedom is never really won. You earn it and you win it in every generation.'" 

The event followed the opening match between Coco Gauff and German player Laura Siegemund, which was won by the former. The 19-year-old reflected on meeting the "Becoming" author at the event and shared that Michelle told her "it’s good to speak up for myself." Referring to her calling out Siegmund for taking extra time between points to the chair umpire, Gauff added: "I think she was happy that I spoke up for myself today."