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Nathan Adrian swam like a man with something to prove.

After a rough season in which he reportedly battled shoulder issues and a disappointing 7th place finish in the finals of the 100 free two days ago, Adrian dropped the hammer in the semi-finals of the 50 free this evening.

Adrian’s time of 21.37 broke Cullen Jones’s American Record time of 21.40, set in the semi-finals of the 2009 FINA World Championships in Rome, Italy, during the supersuited era.

In the post-race interview, Adrian said that he was feeling good today, and decided to “go for it.”

His time in the fastest in the world this year, and also sets him up as the top seed going into tomorrow night’s final. The United States men haven’t picked up a medal in this event since Ben Wildman-Tobriner and Jones went 1-2 in the finals of the 2007 World Championships in Melbourne, Australia.

If Adrian is to win gold here in Kazan, he’ll have to beat out reigning Olympic 50m free champion, Florent Manaudou, who had the second-fastest time in the semi-finals, a 21.41, and last year’s Pan Pacific Championships gold medalist, Brazil’s Bruno Fratus, among others.

Adrian also holds the American Record in the yards version of the 50 free short. The short course meters record belongs to teammate Anthony Ervin, who will be facing off against Russia’s Vladimir Morozov shortly in a swim-off for the final spot in tomorrow’s 50 free final.