ATP World No. 358 Mats Rosenkranz was at the receiving end of one of the most bizarre disqualifications in recent tennis history at the Hersonissos Challenger 3 on Wednesday (August 13). The German surrendered his second-round match at the Challenger-level event to qualifier Pietro Fellin despite winning the first set due to a choice he made during a changeover.Rosenkranz has enjoyed a rough ride on the ATP Challenger and ITF Futures circuit since winning his fourth M15 title in Oberhaching, Germany, earlier in February. Before this week, the 26-year-old had dropped 16 of his last 31 matches and arrived in Hersonissos, Greece, with a chip on his shoulder.In his first-round match, Mats Rosenkrancz got the better of Stefanos Tsitsipas' younger brother Petros Tsitsipas by a scoreline of 6-4, 3-6, 7-6(5). Unfortunately, his run ended in the next match as he was defaulted against Italy's Pietro Fellin while leading 7-5 due to bizarre guidelines surrounding time-outs.During the mandatory 120-second break preceding the second set, the German proceeded to go to the toilet for a shower. However, the Code section of the 2025 ATP Rulebook states that "a serious violation warranting an Immediate Default", once reported and acted upon before the next changeover, gives the tournament supervisor the power to call for a disqualification.In this case, although the World No. 358 wasn't admittedly aware that he could not take a shower during breaks between sets, the umpire handed him a code violation, which eventually resulted in a default following discussion with the supervisor.What does ATP Rulebook say about Code Violations from Chair Umpire for shower breaks?Mats Rosenkranz was certainly hard done by during his second-round outing at the ATP Challenger tournament in Hersonissos. And while there is not a specific provision against taking showers during set breaks, the "Code Violations Not Witnessed By Chair Umpire" subheading of the Code section states:"Occasionally, there are code violations by players that are not witnessed by the Chair Umpire. The Line Umpire should immediately approach the Chair Umpire and report the facts of the violation, during which time the Chair Umpire should turn off all microphones in the area of the chair.""If a serious violation that may warrant an Immediate Default has been reported and acted upon no later than the end of the next changeover, the ATP Supervisor may be called to discuss an Immediate Default. The Supervisor may order the Chair Umpire to issue a code violation for a violation witnessed or not witnessed by the Chair Umpire."Rosenkranz, meanwhile, didn't fare well at both Hersonissos Challenger events he entered this year. Before his second-round exit at this week's Hersonissos 3 event, he had lost in the first round at Hersonissos 2 to the Czech Republic's Martin Engel earlier in March.