#2 To set up an attack by Ronda Rousey

Let's be honest here for a quick second.
Ronda Rousey is most likely absolutely pissed after coming up short against Becky Lynch in the beat the clock challenge and will no doubt take that anger out on Lynch as time goes on. In fact, between Lynch getting beaten down before her match by Charlotte Flair and the massive fan support she received from fans, it would fall in with the underdog story WWE is telling.
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Furthermore, it keeps the story moving forward without a brawl between the three women, which has been overdone lately and has dampened the otherwise white-hot momentum that they have had lately. Of course, WWE is going to have to follow up on that momentum earned through the opening segment by making Rousey's attack on Lynch brutal, which could be the case given the signs.