TENNIS ROUNDUP : Gunnarsson Surprises Becker, 6-3, 7-5

Jan Gunnarsson of Sweden upset defending champion Boris Becker of West Germany, 6-3, 7-5, Thursday at Stockholm, Sweden, in the third round of the $1-million Stockholm Open.

Gunnarsson previous best victory came in 1987, when he beat Mats Wilander of Sweden.

In other matches, Wilander defeated Thomas Muster of Austria, 6-4, 6-7, 6-4; top-seeded Ivan Lendl routed Anders Jarryd of Sweden, 6-0, 6-2; second-seeded Stefan Edberg of Sweden downed Horst Skoff of Austria, 7-5, 6-0; seventh-seeded Tim Mayotte trounced Jens Wohrmann of West Germany, 6-1, 6-1, and Magnus Gustafsson of Sweden defeated Peter Lundgren, also of Sweden, 7-5, 6-1.

Jim Courier was ahead, 6-2, 1-0, when Aaron Krickstein retired because of a foot injury.

Top-seeded John McEnroe turned back Eric Jelen of West Germany, 6-4, 6-1, to reach the quarterfinals of the $440,000 Benson and Hedges tournament at Wembley, England.

In other matches, third-seeded Brad Gilbert defeated Leif Shiras, 7-5, 6-3; second-seeded Michael Chang got past Paul Annacone, who served 13 double-faults, 6-2, 1-6, 6-0, and Wally Masur of Australia overcame Martin Strelba of Czechoslovakia, 7-6, 6-1.

Pam Shriver defeated Anne Smith, 6-4, 6-2, in a second-round match of a Virginia Slims tournament at Chicago.

In other matches, Larisa Savchenko of the Soviet Union beat Bettina Bunge, 6-4, 6-4; Ann Henricksson beat Marianne Werdel, 6-4, 6-7 (4-7), 6-3, and Gretchen Magers of San Diego defeated Kathy Rinaldi, who retired with a pulled hamstring when trailing, 4-6, 7-6 (7-5), 2-0.