Steele Johnson played the waiting game in Friday's 10m preliminary with destiny out of his control after posting an average of 54.33 on his last three dives.
Canada's Maxim Bouchard was in 14th place, well in qualifying position, going into the final round. But he didn't look comfortable atop the tower on his sixth dive and never got close to vertical on entry while attempting an inward 3.5 tuck.
Bouchard's 33.60 score opened the door for Johnson.
The 6-foot-2, 20-year-old American considered his final dive a miss, but when the pool calmed, Johnson clung to the 18th and final qualifying spot by 5.60 points.
"I’m feeling pretty frustrated," Johnson admitted. "I do feel a sense of relief that I was able to get 18th place and am in the semifinals, but with a list like that, I shouldn’t be making a semifinal at an Olympic Games.
"I missed four dives. Personally, I’m not happy with how I performed, but it’s exciting that I get the opportunity to do this again tomorrow. It was a struggle. I definitely knew it was a struggle the whole way through, but you’ve got to keep fighting."
The top 18 divers will be back at the Maria Lenk Aquatics Center Saturday morning for the 10am ET semifinal. And with scores resetting after each round, Johnson has a good a shot as anyone at advancing to the final and taking home a medal.
After all, Johnson's synchronized partner David Boudia placed 18th in the 10m preliminary round in 2012 and he went on to win gold.
Steele Johnson's list
1. Armstand back double free 2.5 twists -- 3.6 -- 70.20
2. Inward 3.5 tuck -- 3.2 -- 86.40
3. Back 3.5 tuck -- 3.3 -- 84.15
4. Forward 4.5 tuck -- 3.7 -- 37.00
5. Reverse 3.5 tuck -- 3.4 -- 61.20
6. Back 2.5 pike 2.5 twists -- 3.6 -- 64.80
Total score: 403.75
USA Diving media service contributed to this report