Before becoming an adored couple on Black Panther, the late Chadwick Boseman and Lupita Nyong'o nearly featured as key characters on another Marvel Cinematic Universe offering as casting director Sarah Halley Finn confirms they nearly appeared in Guardians of the Galaxy.
Source:https://www.cbr.com/black-panther-chadwick-boseman-lupita-nyongo-guardians-of-the-galaxy/