#2 John Cena had not won any World Title yet

Arguably, one of the biggest rivals of Brock Lesnar since his return to WWE in 2012, John Cena has had one of the most successful careers in WWE history. Sure to become a future Hall of Famer, Cena is a record 16-time World Champion in WWE, sharing the record of the most number of World Title reigns with the Nature Boy Ric Flair.
Lesnar returned to WWE in 2012 after WrestleMania 28 and went on to challenge John Cena to an Extreme Rules match, which he lost. But he took a more than decent revenge of the same in 2014 when he almost squashed the Leader of Cenation at SummerSlam to dethrone him as the WWE World Heavyweight Champion - the foundation of the Suplex City.
Look who just shut down all of Tony Khan's critics! More HERE.
Interestingly, when Lesnar last wrestled on SmackDown against Hardcore Holly, Cena had not won a single World title yet. It was in 2005 when Cena defeated JBL at WrestleMania 21 to win his first World World Championship. This was when the spinner belt was introduced by him.
From then till now, Cena has gone from being a rookie to one of the biggest legends in the business, leading the charge of WWE's PG era.