Don’t try to stare down Michael Phelps.

South African swimmer Chad Le Clos learned that lesson in the 200m butterfly semifinals on Monday night after trying to psych out Phelps ahead of their race. NBC’s television coverage caught Le Clos trying to lock eyes with Phelps and shadow boxing in front of the record-setting swimmer—and Phelps was having none of it:

Even as the South African bounced around, Phelps didn’t acknowledge Le Clos at all—he just sat, listened to music (Rage Against the Machine, maybe?), and glared with utterly primal ferocity before the second heat of the event.

Le Clos and Phelps were facing off for the first time in the event in four years, their first race since Le Clos stunned Phelps at the London Olympics by just five hundredths of a second to win the gold medal, which Phelps had claimed in 2004 and 2008.

Le Clos tried to engage with Phelps once they were on the starting blocks for the race—staring at Phelps and trying to lock his gaze—but once again, Phelps kept his icy focus on the pool. But even being in the water didn’t stop Le Clos from checking out what Phelps was doing—the NBC coverage caught Le Clos getting a peek at his rival mid-race:

It was just a semifinal, of course—so without any real bragging rights on the table, Phelps finished second in 1:54.12 and Le Clos in third at 1:55.19, both behind Hungary’s Tamas Kenderesi at 1:53.96. Phelps is set to race in his fifth career butterfly final on Tuesday night, and they might even be in adjacent lanes.

One thing’s for sure, though: There will be some fireworks between the two on Tuesday.