Undefeated heavyweight contender Anthony Joshua has 15 knockouts í hans 15 faglega berst. Check out this video compilation from SHOWTIME Sports showcasing all of Joshua’s KOs. And tune in laugardag to watch the 2012 British Olympic Gold Medalist challenge undefeated American titlist Charles Martin for the IBF Heavyweight World Championship, lifa á Showtime á 5 p.m. OG/2 p.m. PT from The O2 in London.