DARPA's Air Combat Evolution program (ACE) began with AIs fighting each other in a simulated environment in a tournament. Then the winning AI fought against a human (USAF Fighter Weapons School graduate) in that simulated environment, and won. The company that developed the winning AI, Shield AI, has gone on to deploy an AI in an actual F-16 that has flown against a human in trials.
https://www.darpa.mil/program/air-combat-evolution