In one of the biggest grudge matches in the ongoing 2016 Rio Olympics, American swimmer Lily King managed to beat her biggest rival, Russia's Yulia Efimova, earning a gold medal in the 100-meter-breaststroke event on Monday.

The American and Russian swimmer had been at odds with each other, especially after Efimova waved her finger in a "no. 1" gesture at King during the semifinals. Since then, the two swimmers had carried bad blood.

"You're shaking your finger no. 1, and you've been caught for drug cheating. I'm just not a fan. I'm going to go swim my heart out for the U.S.A. and hopefully that turns out the best," King said.

At the center of the drama between the two professional athletes were doping allegations against the Russian swimmer. Efimova had previously tested positive for meldonium, a drug that has recently been banned in the Olympics. Prior to the Rio Olympics, the 24-year-old Russian swimmer had served a 16-month suspension for doping.

This year alone, Efimova almost did not make it to Rio, as she was initially banned from the event after testing positive for the banned drug once more. Efimova appealed the decision, and she was eventually allowed to compete.

Nevertheless, she has been largely considered as one of the most controversial athletes of the current Olympics.

As the 100-meter-breaststroke event ended on Monday, King celebrated with teammate Katie Meili, who won the bronze medal. Efimova, who won silver, was in tears. The two American swimmers largely ignored the Russian athlete during their victory celebration.

"It just proves you can compete clean and still come out on top with all the hard work you put in behind the scenes, behind the meet, at practice and weight sessions. There is a way to become the best and do it the right way," King said in a statement.

With most of the stadium booing her all throughout the event, and with her rival beating her completely, Efimova later stated that she really didn't know how she managed to stay in the competition.

"I really don't know how I even reached the final. It would have really been the end of a fairytale, a horrible dream, if I'd won gold. But that was all I could do right now," the Russian athlete said.

Lily King finished the event with an impressive 1:04.93, Efimova finished almost half a second later, at 1:05.50, while Meili finished at 1:05.69. 

Tags: Rio Olympics lily king 100 meter breaststroke yulia efimova doping