This year's SummerSlam has a huge main event as John Cena defends the WWE World Heavyweight Champion against the "beast incarnate" Brock Lesnar, who is managed by the great Paul Heyman. It isn't their first big matchup and it may not be the last one. They are two guys who have a long history together even Lesnar was out of WWE for eight years while Cena became the unquestionable face of the company. When they have their match at SummerSlam there's a very good chance that WWE will mention their terrific match at Extreme Rules 2012 that was won by Cena. They can mention it and use it as a way of saying that Lesnar is going to be motivated to win not just to be WWE Champion, but to avenge that loss also. What about their feud in 2003? The chances are good that WWE will completely ignore it. They should acknowledge it in some way, but we all know that WWE likes to ignore certain parts of their history. It's not like they're going to go out of their way to talk about it. That's what we're for. Before you get ready for the SummerSlam match you need a refresher about their history. It will be done in chronological order and focus mainly on what they did in their early careers. Here are the ten things you need to know about the history of Brock Lesnar's rivalry with John Cena.