It wasn't easy, but the 37-year-old former YouTube sensation and MMA fighter, Kimbo Slice is now 3-0 on his professional boxing career.

His first two bouts ended in quick knockouts, but when Slice took on Charles Hackmann, a debuting fighter who also works as a fitness trainer, things didn't exactly go the same way. He still eventually won the four round affair with the scores 39-37 across the board, but not before almost losing the fight during the second round.

After winning the first round, Kimbo began to slow down a bit before eating several hard shots that had him severely rocked and leaning to the ropes to try and recover. Hackmann, almost pulled off the upset, but unfortunately for him, those were the only significant shots he landed, as both men looked sloppy and completely exhausted on the third and fourth rounds.

It didn't look good, and it's definitely not the "injection to the heavyweight division" the Shaws were hoping for.

Check out the video after the jump.

HT: JMMANow via IronForgesIron