Pudzianowski secured a takedown early in the fight and was then able to dominate Esch with ground and pound. Esch, unable to get back to his feet during the attack, tapped out to the strikes, making Pudzianowski the winner by submission at 1:15 of the first round. He came into the fight notably slimmer, having lost around 20 lbs from his previous fight. Many believe his large muscle mass to have caused his stamina problems in his earlier fights. On 21 May 2011 Pudzianowski fought James Thompson at KSW 16, losing by arm triangle. In September 2011 Mariusz Pudzianowski started professional training in the well known MMA camp in the USA – American Top Team. Pudzianowski fought on the KSW 17 event, which was held on 26 November 2011. He faced James Thompson in a rematch. He won the fight via majority decision. This decision caused controversy as Thompson had virtually full control in both rounds, and after the fight Thompson, who was clearly angered by the decision, took the microphone from the announcer and launched a verbal assault directed at the promotion in which he ranted: "Fucking joke. Give Mariusz a big round of applause. Come on. What a fucking joke. I thought KSW was really trying to be serious. If you can watch that back and call that serious, then (looking at the promoter) you're fucked, and KSW is going down the fucking toilet." Two days later the promotion changed the result to a No Contest. During a conference held on 28 November, the ruling was deemed to be a "judge's error" and the fight result was changed. Mariusz's next opponent was Bob Sapp in a fight took place in Lodz, Poland on KSW 19 on 12 May 2012. Mariusz won via a TKO in the first round, battering Sapp with a barrage of punching and securing a takedown followed with more punches to win just 39 seconds into the fight. Mariusz then faced Christos Piliafas on 15 September in the main event of KSW 20. Mariusz won via TKO in the first round, after dominating Piliafas on his feet, he then secured a takedown followed by posturing up and raining down some ground and pound to win at 3:48 seconds into the fight. On 8 June 2013, Pudzianowski fought Sean McCorkle at KSW 23, losing the bout in the first round by kimura submission. Pudzianowski fought McCorkle