John Cena has just admitted he is afraid of a former WWE champion. This star is one of Cena's greatest rivals.Cena and Brock Lesnar are two of the greatest WWE rivals over the past 15 years. When Brock first returned to WWE, he targeted Cena. Since then, the two of them have had plenty of brutal matches. Lesnar even destroyed Cena during their SummerSlam 2014 match. The Beast hit the Cenation leader with 16 suplexes during the bout. Recently, the former UFC Champion returned to the Stamford-based promotion and attacked Cena. Now, these two men are set to lock horns in the ring at Wrestlepalooza.Tonight on WWE RAW, Cena kicked off the show. He addressed his upcoming match against Brock Lesnar and even called The Beast one of his toughest challenges. He said that he agreed to face Lesnar because of the fans. He also admitted that he is afraid of The Beast, and he might even fail in their match at Wrestlepalooza, but he will not back down from the former UFC Champion. The Last Real Champion said he doesn't care how many suplexes he has to take; he is ready for war at Wrestlepalooza.Sam Roberts wants Drew McIntyre to be John Cena's final opponentEver since Cena announced his retirement tour, there has been a lot of speculation regarding who will be his final opponent. Fans have speculated a lot of names who could face the Cenation leader.Speaking on his Notsam Wrestling podcast, Sam Roberts said that Drew McIntyre should be the Cenation leader's final opponent."The last one is John Cena versus Drew McIntyre. And that's where you get the John Cena loss. That's where you get Drew McIntyre taking the dub because you can't have John Cena lose a bunch of matches, which just doesn't make any sense because if you have him lose all the matches, there's no value in getting those victories," Roberts said.It will be interesting to see whether WWE will book Drew McIntyre against Cena during the latter's retirement tour.