Tennis Roundup : Wimbledon’s Junior Champion Surprises Gunthardt at Geneva

Wimbledon junior champion Leonardo Lavalle of Mexico upset seventh-seeded Heinz Gunthardt of Switzerland, 6-4, 6-3, Thursday to advance to the quarterfinals of the $100,000 Martini Open tennis tournament at Geneva, Switzerland.

Lavalle, 18, dominated the match as Gunthardt, fresh from playing in the United States on faster surfaces, was unable to change his game to master the clay court at the Eaux Vives Tennis Club.

Second-seeded Joakim Nystrom of Sweden, suffering from an ear, nose and throat ailment, was forced to default to Juan Aguilera, putting the Spaniard into the quarterfinals against Lavalle.

In another match, top-seeded Mats Wilander of Sweden took just 51 minutes to rout Alexander Zverev of the Soviet Union, 6-2, 6-3.

Today, Wilander will play Jakob Hlasek of Switzerland, who advanced by beating Pavel Slozil of Czechoslovakia on Wednesday.

Sue Mascarin upset sixth-seeded Carling Bassett of Canada, 7-6, 6-4, in a Virginia Slims tournament at Chicago.

Bassett took a 5-0 lead in the opening set, but Mascarin rallied to win six straight games and eventually force a tiebreaker.

In the second set, Mascarin went ahead, 5-1, before Bassett stormed back, breaking Mascarin’s service twice. But Bassett failed to hold her serve in the ninth game and netted a service return on match point in the 10th game.

In another second-round match, fourth-seeded Wendy Turnbull of Australia defeated Kate Gompert, 6-4, 6-3.

Top-seeded Jose-Luis Clerc of Argentina defeated of Britain’s Steven Shaw, 6-1, 7-5, to gain the quarterfinals of the $100,000 Nabisco Grand Prix tennis tournament in Bordeaux, France.

Clerc will face Haiti’s Ronald Agenor today. Agenor defeated Huub van Boechel of the Netherlands, 6-4, 6-7, 6-0.