American swimmer Hunter Armstrong shockingly overcame a nightmare scenario during his 100-meter backstroke semifinal at U.S. Olympic trials Sunday to qualify for Monday’s final.

The 23-year-old qualified for the semifinals with the top time of 52.95 — the only swimmer to break the 53-second mark, making him a favorite to qualify for the top-8 final. But a disastrous start left Armstrong playing catchup for most of the race, putting in jeopardy his hopes of making the final and having a chance to return to the Olympics in the 100 back.

His heart “dropped,” he told NBC Sports afterward.

After hitting the wall last at the 50-meter mark, Armstrong managed to catch and pass most of the field and finished second with a time of 53.57. He’ll enter Monday night’s 100 back final ranked fourth behind Ryan Murphy, Adam Chaney and Jack Aikins, respectively.

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Armstrong — who finished ninth in the 100 back at the 2021 Tokyo Olympics and is currently ranked sixth internationally, per World Aquatics — said the camera setup in his lane was in his way and he slipped pushing off at the start.

“I kind of knew something was off,” Armstrong told NBC Sports. “The camera that they put on the blocks was right where I wanted to put my hand. So I kind of pushed it a little bit. But yeah, the wedge just didn't set. As soon as they said go, I slipped.

“Fortunately, the underwaters are not my strongest suit anyway, so I just came up and tried to make it back.”

It was the kind of moment that surely keeps swimmers up at night, but Armstrong responded with an incredible recovery.

This article originally appeared on USA TODAY: US Olympic swimmer overcomes disaster to advance at trials