Michael Phelps takes his pre-competition time very seriously.
The 31-year-old swimmer was caught by cameras with a pretty epic death stare on Monday before his big 200-meter butterfly semifinal race, as his rival, South Africa’s Chad Le Clos, danced close to him. Clearly, it's personal -- Le Clos beat the 19-time gold medalist in the same event in the 2012 Games.
Behold, Phelps' "not having it" face.
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Not surprisingly, the commentators -- who openly laughed and compared Phelps' stare to a "growling dog" -- and social media had a field day.
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Watch the video below to relive supermodel Gisele Bundchen's dazzling return to the runway during Rio's Opening Ceremony.