2. Brock Lesnar's interference:
Although it has been touted that Lesnar will not appear at Extreme Rules, in the world of wrestling, nothing is certain. The WWE Universal Champion recently appeared at UFC 226, where he shoved Daniel Cormier after the latter's victory. He has since entered the USADA testing pool, meaning that he is looking to get back to UFC.
With his contract with WWE said to last through August, he is expected to defend his Universal Championship at SummerSlam.
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You can watch Brock Lesnar attack Roman Reigns here:
Roman Reigns and Bobby Lashley are set to face each other at Extreme Rules, in what could be the main event of the night. The winner of that bout is expected to go on to face Lesnar at SummerSlam. Lesnar is not advertised for the show, but 'The Beast' could appear to interfere and attack either of the two men.
In such a case, the bout would end in a Double Disqualification, with perhaps both men facing Lesnar at SummerSlam.