Lyles was a class apart and the young challenger, Erriyon Knighton, 18, was no better than third in 19.80.
He came here as world number one with the super time of 19.49.
Kenneth Bednarek was second in 19.77 and it was an American triple.
And there was wild American victory joy with flags and an ecstatic crowd at Hayward Field.
The 200 finals turned out to be something very special for both men and women.
There was a charge in the air that remained.
Only Usain Bolt, 19.19 and Yohan Blake 19.26 have run faster in history.
For Americans, Michael Johnson's 19.32 from the Olympics in Atlanta in 1996 means something very special.
- This fight between Lyles and Knighton did not happen.
It's not so strange after 19.31, says SVT Sports expert Alhaji Jeng.
- It feels good to win my first medal, or is it my first medal?
Yes it is and it feels good, says Knighton inside the arena.