Cliff Drysdale, who epitomizes the professional tennis player as suave sophisticate, has no goals as a player these days except to do well enough to justify staying on the tour six months a year enjoying the good life he relishes.

The urbane, articulate, universally popular 35-year-old South African who now lives in Texas hill country outside Austin and spends his other half-year as director of tennis at the Lakeway WOrld of Tennis, says that his friends on the circuit kid him abotu being an old man and ask him each day if he has taken his Geritol.

But Drysdale, a semifinalist at Wimbledon and the French Championships in 1967 and a member of the original "Handsome Eight" touring troupe of World Championship Tennis (WCT) in 1968, played like a colt today in b eating one of his best friends, Mark Cox. 6-3, 6-1, in the second round of the $200,000 U.S. Pro Indoor.

Cox was seeded No. 12 in the strong 50-man field for the tournament at the Spectrum, the biggest of 12 events in World Championship Tennis renamed "World Series of Tennis," which leads to rich playoffs at Kansas City (doubles) and Dalias (singles) in May.

Cox, a 33-year-old graduzte in economies from Cambridge is No. 1 in the British men's rankings announced two weeks ago.

The lefthander has played well in recent months. He beat Wojtek Fibak, Jimmy Connors adn Manuel Orantes to win the Stockholm Open in October and was a semifinalist in two other fall Grand Prix tournaments.

Cox has won all three of his singles matches in the King's Cup. a European team competition, in recent days, and was perhaps fatigued, having come to Philadelphia from contests in Yugoslavia and Britain.

Certainly he had difficulty adjusting to the lighter balls used on this side of the Atlantci. "The ball seemed to be shooting off the court, with a much higher and more lively bounce than what I've been used to," said Cox, who hastily rearranged his schedule to leave tonight and rejoin his British teammate for another King's Cup match in Germany.

"There were a few bad bounces, too," added Drysdale, who says the most pleasant year he ever spent was the season he played doubles with Cox. "I think that disturbed his rhythm a little bit. Mark's game doesn't leave much margin for error."

Drysdale made an interesting comparison between the hard-hitting Cox, whose best stroke is a flat forehand, and Connors, the top-seeded defending champion here.

"They play similarly. WHen Mark is playing well, there's not much you can do against him, even though you know he's going to go cross-court on his backhand nearly all the time," said Drysdale, who read Cox's passing shots perfectly and covered them.

"Both he and Connors are quite predictable, but if they're executing well, it is difficult to do much against them even if you know what they're going to do."

Today, though, it was the ambidex- trous Drysdale who did everything right, making hardly an unforced error, winning many long rallies with his potent two-fisted backhand, which he was using when Chris Evert and Bjorn Borg (the No. 2 seed here) were mere tots.

"It's difficult to get angry with Cliff." said Cox, who never did find his timing, "because he's so relaxed as he wanders around the court he looks as if he's out for an afternoon stroll."

In other matches, 12th-seeded Dick Stockton let John Alexander off the hook several times, but finally put him away, 6-4, 6-7, 7-6; fifth-seeded Adriano Panatta beat Tom Gorman, 6-4, 3-6, 6-4, and Jeff Borowiak ousted 15th-seeded Vitas Gerulaitis, runnerup here two years ago, 6-4, 4-6, 6-4.

Stockton served for the match in the second set, had two match points in the ensuing tle breaker that the eventually lost, 7 points to 6, and had three match points on Alexander's serve in the last game before sudden death in the final set.

But Alexander, after missing his first serve at 0-40, won five points in a row, one on a lunging volley off a good passing-shot attempt, to force the final tie breaker. He lost it 7-4, after trailing 0-5.

"It was one of those matches where I felt I was on top all the way, I had a lot of chances and was sure I would win eventually," said Stockton, who finally clinched it with a topspin lob that winner that Alexander could only leap and wave at - an appropriate shot, since Stockton had lobbers well throughout.

"I just didn't know how or when I would win," Stockton said with a grin. "I think if I had lost the third set. I'd have asked them to make it three of five."

Panetta beat Gorman a semifinalist in the Baltimore International last week, by breaking him in the final game, aided by a double fault to 0.30 after Gorman had been distracted by play on adjacent court.