Martin Rogers

USA TODAY Sports

RIO DE JANEIRO — American swimmer Lilly King set up a Monday night grudge match against Russian drug cheat Yulia Efimova with a heavy dose of “trash-talking” and a Dikembe Mutombo-style finger wave following Sunday’s 100-meter breaststroke semifinals.

After Efimova, the crowd villain at the Olympic Aquatics Stadium after being controversially restored to the Games on Saturday following a previous ban, posted 1:05.72 in the first semifinal, she appeared to mock King by waggling her index finger — King had first performed the move earlier in the day.

King, 19, refused to back down. The American youngster was waiting in the ready room ahead of her swim in the second semifinal, made eye contact with Efimova, then sparred back with a finger shake and a fierce glare of her own.

Then, she backed it up, with both actions and words. King swam 1:05.70 to claim the top seed position for the final, then unloaded on Efimova during a post-race interview.

“Basically, what happened this morning was that I finished and then I waved my finger a little bit, because that’s kind of how I am,” King said. “Then tonight just now Yulia got done with her swim and I am watching in the ready room — and there she is there shaking her finger. So then I got done and I beat her time so I waved my finger again. People probably think I am serving it up a little bit but that is just how I am.

“That’s just my personality. I’m not this sweet little girl, that’s not who I am. If I do need to stir it up to put a little fire under my butt or anybody else then that’s what I’m going to do."

Swimmers don’t tend to get booed too often but the crowd showed no hesitation in turning its ire on Efimova, who served a 16-month suspension that spanned from late 2013 to February 2015. She also failed a test for meldonium earlier this year, only for the result to be later overturned.

Efimova refused to speak to reporters after her semifinal swim.

King only found out on Saturday that Efimova would be competing. The Russian had been banned after being linked with a World Anti-Doping Agency report into systematic government-backed doping in Russian sport. International swimming chiefs have still offered no explanation as to why she was reinstated.

“I am a little bit (happy),” King added. “It always increases the comp and the pressure and I’m always up for the challenge. (The booing) is unfortunate but that was her decision and that’s what’s going to happen.”

In regards to whether Efimova should be allowed to compete, King said: “It’s not my decision, it’s the IOC’s decision — even though its not something I agree with.”

Follow Martin Rogers on Twitter @mrogersUSAT.