Stan Smith and Cliff Richey, who monopolized the No. 1 U.S. ranking from 1969 through 1972, were upset in the first round of the $125,000 Washington Star International tennis championships yesterday in steamy midday heat that made the Washington Tennis Stadium seem like an open-air sauna with a floor of clay.

Both 30-year-olds appeared to have their sharpness melted and their minds dazed by the stifling sun as they were beaten in straightsets by 28-year-old journeymen who love the nomadic life-style of the pro tennis tour, but have no false hopes of achieving the glory their victims have known.

Smith fell to Alexander (Zan) Guerry of Houston, via Lookout Mountain, Tenn., 6-3, 6-3. Richey, who defaulted with a bad leg in Cincinnati last week and almost didn't play here, was put out of his misery by South African John Yuill, 6-3, 6-2.

Smith, who has been working diligently this year to reattain the form that made him the top-ranked U.S. player in 1969-71-72 and co-No. 1 with Jimmy Connors in 1973, was seeded No. 7 in the 64-man field. Richey, who won the Star tournament in 1970 and edged Smith for the top U.S. rating on the last day of that season, was No. 13 here.

Third-seeded Raul Ramirez, the Mexican Davis Cup and defending Grand Pric champion who was runner-up to Connors here last year, was ousted early yesterday morning by Californian Brian Teacher, 6-4, 4-6, 7-6, in the last match of the opening-day program, which was twice interrupted by tropical downpours.

No. 10 seed Jaime Pillol withdrew before his first-round matches today because of a heavy cold.

Guerry and Yuill, the conquerors of the moment, come from different hemispheres but have strikingly similar attitudes toward pro tennis and their place in it. Nos. 123 and 73, respectively, in the computer rankings of the Associations of Tennis Professionals, they are realistic and know they will never be world-beaters.

They merely want to make a decent living as long as they can in the soft underbelly of a profession they enjoy. Guerry is married and has a 6-year-old daughter. Yuill is an easygoing bachelor who relishes a playboy image. They both like to travel, meet people, and squeeze the most they can out of modest abilities on the court.

Guerry grew up in Lookout Mountain, fashionable Chattanooga suburb, and was the best player in town until Roscoe Tanner, who lived less than a half-mile away, matured.

He played on the circuit until graduating from Rice University in 1971. His best win, ironiaclly, was over Smith in Houston when Smith was ranked No. 1 but still unaccustomed to the clay courts that now dominate outdoor pro tournaments, to the detriment of the big-serve-and volley players who ruled on faster courts until about 1974.

Guerry went to Wharton Business School and was a financial planner for two years for Texas Commerce Bank in his adopted hoemtown of Houston. Last year he decided to give pro tennis another fling and played the Southern Circuit, 10 satellite events with a total of just over $100,000 in prize money.

He has played occasional Grand Prix events and this year finished second on the Southern Circuit, sweating in weather and court conditions similar to those here while more accomplished players were in Europe, competing in the French Open, Wimbledon and points between.

"I don't think Stan has quite adjusted his game back from grass to clay," Guerry said after his crambling, satisfying victory yesterday. "He seemed a bit uncertain as to when to attack and when to stay back. It takes a while to adjust the ground strokes, especially the backhand, to get back the rhythm and control and patience you need on clay.

"I think the heat bothered him more, too. It was to my advantage to play in the afternoon. I wouldn't want to play Harold Solomon at noon, but I would just about anyone else."

It was Solomon, the golden regriever, who rekindled Guerry's interest in the pro circuit. They were team-mates and best friends at Rice when Guerry was a senior and Solomon a freshman. Solomon taught Geurry the two fisted backhand four years ago, and that helped ameliorate his most glaring weakness.

"Guys like Smith, Ashe, Bob Lutz, Charlie Pasarell, Dick Stockton, who have great serves and volleys, used to kill me. They would always chip to my backhand and come in. The sharply angled backhand is the only thing that could keep them off the net, and that's what the two-fister gives you.

"I had too many technical limitations. I could see the handwriting on the wall. There was no place for me to go. Not that there's any place now, really, but at least with the new backhand I felt I had eliminated a big weakness."

Yuill, who had never before played Richey, has been a pro for six years with little fanfare.

"I wanted to travel and see the world. Tennis was a cheap way to do it," he said yesterday, casual as ever, his long, lank blond hair matted with perspiration as he puffed on one of the 20 cigarettes he smokes every day, "even though I know they destroy my lungs."

"I never intended to be a pro," he continued. "I played tennis on weekends when I was at Natal University in Durban. I've never had a coach or a lesson in my life.

"But I really enjoy the life, I'm not fool enough to think that I'm going to be No. 1 in the world or anything like that. I have no false ambitions. But as long as I make a decent living and enjoy it, I'll keep it up.

"Last year my ranking slipped and I thought seriously about giving it up. I didn't want to go back into the qualifying. I've been through that and it's absolutely a dog's life. Very depressing. But then I hit a good patch and was all right again."

Yuill's best assets are his serve and volley, but unlike most exponents of the "big game," he prefers clay and feels he serves and volleys best on this surface. He also takes particular pride in ironing out his own wrinkles when they crop up in his essentially smooth game.

If Guerry and Yuill have a good deal in common, however, their back-to-back victories over great AMerican workhorses who ain't quite what they used to be were markedly different.

Guerry scampered all over the court, his mop of brown hair, shirt tail, and the towel tucked in his waistband all flying in different directions as he dug and slid and scooted for retrieves. "I was kind of indevisive and sloppy," Smith said, but Guerry's stream of passing shots certainly added to the indecision.

Yuill, by contrast, followed his first serve to the net frequently, getting in whenever he could for clean volleys, and stayed back the rest of the time hitting steady, unspectacular ground strokes, letting Richey make all the mistakes.

"I didn't rush or get uptight or use up an'y nervous energy. I never pushed," Yuill said. "I let him take the initiative and counterattacked. If I had run around like a maniac, I never could have lasted. I thought I played quite well, quite cleverly, in those conditions. I relaxed and conserved energy."

FIRST SINGLES

Matt Mitchell def. Marcelo Lara, 6-4, 7-5; Hank Pfister def. Ismail el Shafei, 6-7, 6-0, 6-4; Butch Seewagen def. Paul Dronk, 6-1, 6-3; Hans Gildemester def. Jeff Austin, 6-2, 6-2; Brian Fairlie def. Eliot Teltscher, 6-3, 6-4; Zan Guerry def. Stan Smith, 6-3, 6-3; Tim Wilkinson def. John Feaver, 6-4, 6-3; John Yuill def. Cliff RIchey, 6-3, 6-2, Tom Gullikson def. Doug Crawford, 6-2, 6-2.

FIRST-ROUND DOUBLES

John Yuill-John James def. Bruce Manson-Eliot Teltscher, 6-4, 6-4; Tito Vasquez-Ricardo Ucasa def. Deon Joubert-Willem Prinsloo, 6-3, 1-6, 6-3; Joh Witlinger-Tim Wilkinson def. George Hardie-Dick Bohrnstedt, 6-1, 6-4.

TODAY'S SCHEDULE

Stadium Court

Noon - Roscoe Tanner vs. Dick Bohrnstedt, followed by Guillermo Vilas vs. Larry Gottfried, Raul Ramirez-Brian Gottfried vs. Anand Amritrai-Dick Crealy, Harold Solomon vs. John McEnroe, Sherwood Stewart-Freddie McNair vs. Lito Alvarez-Victor Pecci.

Granstand A-1

11 a.m. - Bob Hewitt vs. Alvaro Betancur, followed by Dick Crealy vs. Tim Gullikson, Zan Guerry vs. Tim Wilkinson, Gene Mayer vs. Eddie Dibbs or Sherwood Stewart, Bob Hewitt-Roscoe Tanner vs. Byron Bertram-Bernie Mitton. Tim Gullikson-Tom Gullikson vs. Mark Edmondson-John Marks.

Grandstand A-2

11 a.m. - John Alexander vs. Mike Cahill, followed by Brian Fairlie vs. Freddie McNair or Terry Moor, Matt Mitchell vs. Tom Gullikson or Victor Pecci, Zellko Franulovic-Frank Gebert vs. Van Winitsky-Rick Fagel, Pat Cornejo-Jaime Filloi vs. Jorge Andrew-Emilio Montano.

Grandstand B-1

11 a.m. - Phil Dent vs. Frank Gebert, followed by Ray Moore vs. John Yuill, Lito Alvarez vs. Bruce Manson, Ismail el Shafei-Brian Fairlie vs. Hans Gildemeister-Francisco Gonzalez, John Alexander-Phil Dent vs. Ray Moore-David Schneider.

Grandstand B-3

11 a.m. - Byron Bertram vs. Hans Gildemeister, followed by Zeliko Franulovic vs. Trey Walike, Ricardo Cano vs. Butch Seewagen.