Tony Thompson has already been stopped by Wladimir Klitschko once in his career, but the American heavyweight is talking tough ahead of a mandatory title bout rematch with the Ukrainian star in July. \"I\'m ready,\" Thompson said. \"I\'m looking forward to becoming the heavyweight champion of the world.\" Klitschko improved to 57-3 with his 50th career knockout Saturday, stopping Frenchman Jean-Marc Mormeck in the fifth round at Dusseldorf, Germany, to retain the International Boxing Federation and World Boxing Association titles. \"I wasn\'t really impressed with either performance. It was an infomercial at best,\" Thompson said. \"Mormeck is a tough cruiserweight but he\'s not an impressive opponent for the heavyweight champion of the world.\" Thompson, 36-2 with 24 knockouts, is the mandatory IBF challenger and set to face Klitschko by mid-July. The 40-year-old US southpaw felt Klitschko snubbed him by mentioning other potential rivals to his throne without a nod his way. \"It was interesting that it seemed that Wladimir mentioned everyone in the division but me,\" Thompson said. \"I knew my shot was next, and I\'m doing everything to solely focus on beating him. \"I just want to fight. It doesn\'t matter to me where it takes place. If he wants to come over here, great. If he wants to fight in Germany that\'s great too.\" Klitschko stopped Thompson in the 11th round in 2008 at Hamburg, ending Thompson\'s 27-fight win streak over an eight-year span. Since then, Thompson has won five fights in a row, none of them going the distance. Klitschko\'s brother Vitali owns the World Boxing Council heavyweight throne and the siblings have said they will never fight each either, leaving a lacklustre set of rivals to challenge their reign.