Eagle-eyed observers of the men's 50m freestyle at the Australian Olympic Trials on Wednesday night would have noticed something that looked a little out of place.

In lane five at the Brisbane Aquatic Centre, Ben Armbruster was sporting a white cap, emblazoned with "Armbruster" as is standard.

So far so good, but also on the cap was the red, black and gold stripes of the German flag.

It's fair to wonder what a boy from Stanthorpe, who trained early in his career in a pool that was only open for six months a year on account of it not being heated, is doing with a German national team cap on, emblazoned with his name.

"When I was at a World Cup last year, I met a fellow called Luca Armbruster," Ben said.

"He's from Germany and that's his cap I was wearing. 

"I think it was a bit of a good luck charm here because he's already made it [to the Olympics].

"He's going. I wanna wear his stuff so I'll go too."

There is no family relationship as far as Australia's Armbruster is aware, but the cap still turned out to be a very effective good luck charm.

The 22-year-old squeaked into the second spot in the men's 50m freestyle by 0.04 seconds, finishing behind Cam McEvoy, and celebrating by slapping the pool and roaring to his supporters.

"Relief. Happiness. It was a mix of everything. You just can't believe it," he said.

"I asked someone to slap me earlier, like, just before, cause I can't, but I feel like I'm dreaming.

"It took me a second to be able to read the board, because everything was a blur.

"I don't remember because I was just so happy. I know I slapped the water. I just lost it."

ABC Sport will be live blogging every day of the Paris Olympics from July 27 (Australian time).

He has every reason to be a mix of thrilled and surprised.

"The 50 free wasn't even in my mind," Ben explained.

"I trained for 100 fly, so everything that helped me do that was just all the hard work and skills and whatnot, and that's what I really relied on tonight.

"Just that skill, that first 15 and my good underwaters. So I just relied on that. And it paid off."

Armbruster has history with making teams in events he's not intending to do well in.

"I feel like when I made the Commonwealth Games with the 50 back, the 50 free was a race just to get me in something I could do if I swam well, but just to get me in, get the nerves down and something to dust the cobwebs off.

"And yeah, history repeats itself."

Armbruster has been on the verge of qualifying for Australian teams for a while, a freak rib injury robbing him of the chance to compete at the 2023 World Championships.

But getting to the Olympics is something else.