The world No 2, hoping to make another challenge to Pete Sampras's No 1 position at next week's French Open, produced his second impressive performance of the week following his thrashing of the world No 7, Sweden's Jonas Bjorkman, in straight sets on Monday. Korda's win gave the Czechs an unbeatable 2-0 lead.
In the second Red Group match, Australia beat Sweden 2-1 and will now face the Czechs today to determine who plays in Sunday's final against the winner of the Blue Group. Eight nations have been taking part.
Korda, the Australian Open champion, needed two hours and 27 minutes to defeat Chang, the 1989 French Open champion, who he said was "as fast as Speedy Gonzales".
Slava Dosedel thrashed Jim Courier 6-3, 6-1 in the first singles. The American, another former French Open champion, lost for the second time this week.
The tie between Australia and Sweden was decided by Todd Woodbridge and Mark Woodforde's 6-3, 2-6, 6-3 win over Bjorkman and Mikael Tillstrom after the singles matches had been split.
Australia's Mark Philippoussis hit four aces in one game during his 6- 3, 6-4 win over Bjorkman. Sweden's Magnus Norman then captured the second singles by sweeping past Woodforde 6-2, 6-3.
Germany, the defending champions, Spain, Slovakia and France are in the Blue Group.