My favorite zone match was Wimbledon 1980 finals. Evonne Goolagong started the match completely "zoning" against arch rival Chris Evert (Lloyd). Before you could bat an eyelash Evonne was up 6-1 and 3-0 in the second. She was doing nothing wrong and everything effortlessly right, even out dueling Chris from her beloved baseline. Then the rain delay came and when the match began again Evonne was still very much in the zone, but nerves had crept in a bit. She overcame Evert's late comeback and took the match 6-1, 7-6. It was glorius!
My other favorite zone match was really even more amazing but not as dear to my heart. It was the already mentioned Mary Pierce over Steffi Graf in the French Open semis of 1994. I think it was one of those rare instances when a player (Pierce) NEVER leaves the zone against a top notch player (Graf). I think the very first ball struck was a Graf first serve that Pierce slammed back for a winner. You just had the feelign right then and there this was going to be soemthing. Mary had been in the zone all tournament and she entered the semis (and the finals) with the least amount of games lost ever. Steffi was nervous but she played well. there was simply nothing she could do. I will never forget that match because Steffi was truly over powered and I don't think it had ever happened before (or since, really). Monica had beaten Steffi about 4 or 5 times but she NEVER overpowered her in the true sense. That day in Paris, Mary stood up to the Graf ball and slammed it back harder, often times going forehand to forehand. I wish I had it on tape!
Other fave zone matches:
Mandlikova/Navratilova USO '85 - they were both in and out of the zone, first set was spectacular
Navrat/Graf USO '91 - Martina made one her last zone trips at the age of 35!
Capriati/Hingis Aussie '01 - Jen was amazing from first to last ball struck. A tour de force.