Simplify the following text for a Grade 7 native English-speaking person.
Original: Kessler won the WBA Super Middleweight regular title on June 21 , 2008 , beating Dimitri Sartison by a 12th round knockout .
Simplified: Kessler faced Dimitri Sartison on June 21 , 2008 , for the vacant WBA Super Middleweight regular title . Kessler won the match by knockout in the 12th round .