Unseeded Michael Chang upset fourth-seeded Michael Pernfors, 6-4, 6-0, Friday night in the quarterfinals of the $415,000 Trans- America Open tennis championships in San Francisco.
In the other evening quarterfinal, John McEnroe beat Tim Wilkin, 2-6, 6-2, 6-2.
In today’s semifinals, McEnroe will face Johan Kriek, who upset second-seeded Kevin Curren, 1-6, 6-4, 6-2, and Chang, 16, of Placentia, will meet qualifier Danie Visser, a South African living in Palm Desert, who beat Paul Annacone, 6-4, 6-4.
Curren, in his match against Pernfors, lost just three points on his serve in the first set. But Kriek came back to win the next two sets.
Top-seeded Mats Wilander of Sweden moved into the semifinals of the $123,400 Sicilian championships at Palermo by struggling past unseeded Claudio Panatta, 4-6, 6-2, 6-3.
In other quarterfinal matches, Guillermo Perez-Roldan of Argentina defeated countryman Horacio de la Pena, 6-4, 7-6, and Thomas Muster of Austria beat Thierry Tulasne of France, 6-4, 6-4.