Cross will replace Alexa Bliss, the 2018 briefcase winner, who was pulled from the match for medical reasons. The exact nature of Bliss' injury has not been made public, but according to Dave Meltzer, the injury is not serious, and is being done more as a precaution, due to the especially-physical nature of ladder matches.
It appears that WWE was leaning toward Cross as a possible replacement for at least a few days now. On Monday's Raw from London, Cross replaced Bliss in a fatal four way match, in which she defeated the Raw brand's three other Money in the Bank representatives in Natalya, Naomi, and Dana Brooke.
Cross will join Brooke, Bayley, and Mandy Rose as first-time Money in the Bank ladder match participants. Prior veterans of the match performing on Sunday night include Natalya, Naomi, Ember Moon, and 2017 match winner Carmella.