Complex sentence: Green won an interim WBC super-middleweight title when he defeated Eric Lucas by a sixth-round knockout on 20 December 2003 in Montreal, Canada, and then defeated New Zealand fighter Sean Sullivan by a unanimous decision on 21 March 2004 in Perth.
Split into simpler sentences: Green won an interim WBC super-middleweight title when he defeated Eric Lucas by a sixth-round knockout on 20 December 2003 in Montreal, Canada. He next defeated New Zealand fighter Sean Sullivan by a unanimous decision on 21 March 2004 in Perth.