Tim Gullikson, Jaime Fillol, Ross Case and Dick Stockton won in round-robin singles, and the teams of Case and Harold Solomon, Gullikson and Fillol advanced to the doubles final of the Prudential-Bache Grand Champions tennis tournament yesterday at Rock Creek Tennis Stadium.

The big winner, however, was the heat.

Solomon, 34, who wheezed his way through a straight-set loss to Bob Lutz Friday night, ran into similar problems in the middle of his match with Gullikson yesterday morning and ended up losing, 4-6, 6-4, 6-1. Later, Solomon had chest and leg cramps.

But after rest and some saltwater intake, he came back to play with Case against Stan Smith and Lutz. In that match, with officials reporting the on-court temperature at 120 degrees in the shade of the umpire's chair, Solomon and Case took a 6-4, 4-1 lead before Lutz -- a 7-5, 6-3 loser to Fillol in a morning singles match -- bowed out. He and Smith, who won the U.S. Open doubles title four times on four surfaces, retired.

"It was too hot for this California boy," Lutz, 39, of San Clemente, said from under a cool, wet towel that didn't appear to help much.

Sherwood Stewart, 40, who came into the event with a strained foot tendon, aggravated the injury Friday night in a 6-4, 6-1 loss to Smith. He gamely limped through a 6-1, 6-1 loss to Case yesterday morning before withdrawing.

"I'm gettin' old, Gull," Stewart said to Gullikson while soaking the foot in a tub of ice water.

"You've got to start pounding that cerveza {beer}," Gullikson replied with a grin. "That carbohydrate-loading, you know."

Gullikson admitted to having downed a few cold carbohydrates after his and Fillol's doubles match late Friday night against Stewart and Stockton was suspended because of rain. (Because of Stewart's withdrawal, Gullikson and Fillol yesterday were declared winners by default.) As it turned out, Gullikson probably needed the added energy.

He fell behind Solomon, 4-6, 4-4, before Solomon began having difficulty. Gullikson ended up winning the second and third sets, 6-4, 6-1.

"Solly just hit the wall again," Gullikson said after the two-hour match.

Solomon, who has a history of developing physical problems when he plays in hot, humid weather, said Friday, "I just couldn't get any air into my lungs." Yesterday, in addition to the breathing difficulty, there were cramps that left the native Washingtonian in a prone position, sipping saltwater.

"It tastes terrible and makes you throw up if you drink it too quickly," Solomon said. "But it's the only thing I know that helps, other than maybe getting in a little better shape."

Even being in great shape doesn't make much difference in oppressive heat, said Stockton. But like the rest of the players, he refused to complain.

"The weather's no different here than it is any other year, although it is hotter here this year than I've ever seen it," said Stockton, who defeated Smith, 4-6, 6-3, 6-3, in singles. "But you can't not have a {Grand Champions} event just because it's hot out. The event here has been very successful. The people here appreciate tennis . . . .

"I think we are fortunate to have the opportunity to play here."

The round-robin singles and single-elimintion doubles continue today at 11 a.m. The singles final, between the players with the best won-lost record in each of the two four-man round-robin groups, is set for 7 p.m. Monday. If Gullikson and Case each win today, they will advance; if not, the finalists will be determined on percentage of sets won. The doubles final will follow the singles final Monday.