Stan Smith and Bob Lutz, used to playing on the same side of the net, will be on opposite sides tonight in the singles final of the Prudential-Bache Grand Champions tournament at Rock Creek Tennis Stadium.

The team of Harold Solomon and Ross Case will meet Tim Gullikson and Jaime Fillol in tonight's doubles final, which will follow a Sovran Bank/D.C. National Tennis Classic first-round singles match between Peter Fleming and John Ross scheduled to begin at 7:30 p.m.

Smith, the winner of round-robin Group A, last night defeated Case, 6-3, 6-4, to reach tonight's 7 o'clock championship. Smith, Case and Dick Stockton all ended the round-robin with 2-1 match records. However, Smith advanced because he won five of seven sets in his three matches; Stockton won five of eight, Case four of seven.

Lutz, who with Smith won the U.S. Open doubles championship four times on four different surfaces, won Group B by defeating Tim Gullikson, 6-4, 6-2, then watched Solomon defeat Fillol in the first set of their match, 7-6 (9-7). Fillol entered the match needing a straight-set victory to advance.

"A lot of people don't understand it," Lutz said of the tie-breaking procedure. "I've gotten used to it because I've been playing on the circuit. But for the rest of the people, it would be a lot easier if Solomon won. It would be more cut and dried that way."

Lutz departed after discovering his fate, and Solomon went on to win the second set, 6-4.

If the tie-breaking process was somewhat unusual, it was not an unfitting ending to the day. At 10 o'clock yesterday morning, it was announced that the start of the day's play, scheduled for 11 a.m., would be postponed until 7 p.m. The players and tournament officials determined that oppressive heat and humidity posed a threat to players.

Saturday at 3 p.m., the temperature under the stadium court's umpire's chair was 117 degrees, officials reported. Solomon and Lutz both suffered symptoms of heat exhaustion after playing Saturday.

"We met with the players late {Saturday} night, and my opinion, based on yesterday's results, was that if there was way possible to postpone, we should do so," said Michelle Boggs, Grand Champions tour executive director.

Lutz, who played singles Saturday morning, was forced to retire in the second set of an afternoon doubles match in which he and Smith were playing Solomon and Case. Lutz developed cramps that sent him to Washington Hospital Center. He was released later in the evening.

Solomon, who had trouble breathing during singles matches Friday night and Saturday morning, developed chest and leg cramps Saturday afternoon. Rest and saltwater intake allowed him to play doubles.

Ticket-holders for yesterday's session were encouraged to watch the final matches of the Sovran Bank/D.C. National Tennis Classic qualifying tournament and allowed to return last night, free of charge, for the Grand Champions matches.

"Next year," Boggs said, "we will schedule as much play as possible for the night."

Lutz thought that was going to happen this year. "When I signed up to play in this event, I thought it was going to be at night," he said. "I was surprised {at the daytime schedule}. It's tough every year when we play here, but high 80s and high 90s are a little different. Plus, the change in surface {from synthetic clay to a hard surface} makes it even hotter. And let's face it, when it's like 120 degrees on the court, it's a little tough when you get to 40."