The 35-year-old – who has two World Championship golds, one Olympic Games gold, and 123 national team goals on her CV – announced as recently as Thursday that Monday's match, where her San Diego faced North Carolina, would be her last.
Morgan is pregnant with her second child and started the match with the captain's armband before being visibly moved and substituted out after just over a quarter of an hour. Shortly before that, the star scored a penalty.
Before the match started, video clips from her 15-year-long and eventful career were shown. She had her four-year-old daughter Charlie with her on the pitch, and nearly 100 relatives were in the stands to follow her farewell from professional football.
After returning from a foot injury in the spring, Morgan was selected for the USA's training matches against South Korea in early June, but she was dropped from the Olympic Games squad by the new national team coach Emma Hayes.
Her last appearance for the national team was thus the 62 minutes Morgan played against South Korea on June 4. The 123 goals she scored for the USA make her the fifth-highest scorer of all time in the national team.
Except for two short stints at Lyon and Tottenham, she has played her entire career in American club teams.