Lilly King, Yulia Efimova

A few months ago, Lilly King was training out of her dorm room at Indiana University. On Monday night, she became an American hero, winning gold in the 100-meter breaststroke at the Rio Olympics. And the victory came with major drama.

On Sunday, Yulia Efimova, the 2015 world champion in the 100 breaststroke, raised a finger, calling herself No. 1 after winning her semifinal. Backstage, King wagged her own finger at the Russian. King then won the second semifinal heat, raised her own finger and called out Efimova on NBC: "You've been caught for drug-cheating. I'm just not a fan."

Efimova was suspended from Oct. 2013-Feb. 2015 for steroid use, and she was temporarily banned for this Olympics after failing a test for meldonium.

In the pool Monday, King and Efimova raced side by side in the middle lanes. At the end, King pulled away for the gold. At 1:04.93, she set an Olympic record. Efimova's time was 1:05.50.

Lilly King, Yulia Efimova

"It's incredible, just winning a gold medal, and knowing I did it clean," King said.

King, 19, talked the talk and walked the walk. Then America celebrated on social media.

There were a lot of Rocky IV references:

King gets a much needed day off Tuesday. She returns to the pool Wednesday for her heat in the 200 breaststroke.

Katie Meili, a 25-year-old Texan, won the bronze medal in the 100 breaststroke and embraced King, as Efimova looked on.

More Olympics:
-- These Were The 5 Best Olympics Ever
-- Why Michael Phelps Has Red Spots
-- Kyrie Irving And Coach K Have 'Unfinished Business'

Follow Jeffrey Eisenband on Twitter @JeffEisenband.