DUBAI, United Arab Emirates — In a throwback to one of tennis' greatest rivalries, seven-time Grand Slam winner John McEnroe beat Bjorn Borg 4-6, 6-4, 10-4 in an exhibition match Thursday. The match was billed as the final showdown between two of tennis' greatest adversaries. They met 14 times in ATP tour, Davis Cup and Grand Slam play, each winning seven times.