WWE has confirmed that Keith Lee has been pulled from the Elimination Chamber card tonight through injury, with a replacement in the US title match also set to be decided on tonight’s show.
John Morrison, Ricochet, Elias and Mustafa Ali will now compete in a four-way match on the kickoff show, with the winner progressing to the United States Championship three-way between Bobby Lashley and Riddle.
— WWE (@WWE) February 21, 2021
Following on from this, Fightful Select is reporting that John Morrison has been discussed as a potential replacement for Keith Lee, but that is by no means confirmed at this stage.
The reason this has not been made into a straight singles between Bobby Lashley and Riddle is because, as revealed by Fightful Select, having three people in the match is integral to the story WWE is trying to tell.