Wladimir Klitschko vs. Ruslan Chagaev, billed as "Knockout Auf Schalke", was a professional boxing match contested on 20 June 2009 for the IBF, WBO, IBO, and vacant The Ring heavyweight championship.

Ultimately, Klitschko reached agreements with Chagaev who agreed to step in for Haye as a last-minute replacement (Valuev's team wanted the fight to be postponed until autumn of that year).

[6][7] In the pre-fight comparison, The Ring was giving Klitschko an advantage in power, speed and athletic ability, as well as experience, while also crediting Chagaev for having better defence, praising him for his fundamentals and footwork.

[8] Veltins-Arena with capacity of over 61,000 seats was sold out, making the audience the biggest for boxing in Germany since 1939, when Max Schmeling knocked out Adolf Heuser in front of 70,000 people in Stuttgart.

Klitschko would make two defences, one against Eddie Chambers and the other one a rematch with former WBC champion Samuel Peter, before a unification bout with then WBA beltholder David Haye in July 2011.