Pat Bradley, full of aspirin and surprises, was awarded a well-deserved footnote in the LPGA history book yesterday.

She halted the record winning streak of Nancy Lopes at five tournaments. Bradley shot a five-under par 67 for 206 and a four-stroke victory over the day's early coleader, Jane Blalock, in the Lady Keystone Open.

The gracious but mentally frazzled Lopez finished 15 strokes back of the winner, tied for 13th.

The 21-year-old rookie began the day eight strokes behind the leaders at three-over par, and the mental fatigue induced by instant stardom caused her putter to quiver.For the first time since she can remember, Lopez did not tally a birdie, even though she had birdie putts from four feet (twice) and five feet. She shot a two-over-par for the second day, finishing five over with 73 74 74 - 221.

"My stroke was good but I couldn't think 'in,'" said Lopez. "I didn't make any putts. I was just tired, mentally tired. I was getting headaches.

"I'm just going to have to slow down a little bit, budget my time better, and concentrate more on golf than other things. I know what I can do, and all I pick up a club for three days.

"I wanted to continue the streak, of course. But I just thank God I've done so well, and that I have so many years to go."

Lopez received a standing ovation at the 18th green from yesterday's crowd of 15,700. By comparison, the attendance last year was 8,000 - for the entire three-day tournament. A warm round of applause awaited her in the press room and when she was through with her interview, a male writer approached her with five golf hats for her to autograph.

Bradley, in accepting her $7,500 first-place check, said over the outdoor microphone, "I would just like to say to Nancy, have a nice vacation. It is well deserved. You are super."

Later, in the press room, Bradley said, "I really don't think it was a question of beating Nancy Lopez. I truly believe that if Nancy was rested, this would have been a different story. I just think Nancy is worn out. She's only human."

Bradley had no bogeys and five birdies, and did not three-put throughout the tournament, turning in a final card of 70-69-67 - 206, a total of 10-under par. Her four-stroke victory margin is the largest of the year in a 54-hole tournament, and it was also her first win of 1978.

Lopez is still the only mulitple winner this year. She has seven victories, a record for both female and male rookies. She is still well in reach of Mickey Wright's record for most LPGA Wins in a year. 13 in 1963., and Judy Rankin's one-year money record, $150,734.28 in 1976.

Lopez's $930 check yesterday raised her 1978 earnings to $131,128, tops in the LPGA. She has already broken records for money earned in a rookie year for both women and men.

Going into the tournament, Lopez had won 7.7 percent of all the prize money offered this year in LPGA tournaments. Had she won 7.7 percent of prizes offered so far to the men, she would have taken home more than $400,000.

Bradley's fine performance, which tied a course record set by Blalock Friday, came despite a painful left thumb that has hindered her about a year. Every day before she plays she takes three aspirin, and during the tournament yesterday a police officer went scurrying to find her some tape to bandage the thumb. Bradley said doctors have not diagnosed the problem.

"I've had problems in the past, shooting 79 in the first round and then coming back with 65s," said Bradley, a 27-year-old, fifth-year pro with three career wins. "I missed a few fairways today but I had faith in my putter. I'm just pleased to be the winner."

Third place went to Joyce Kazmierski, who also tied the course record 67 to finish 73-73-67, seven strokes back of Bradley.

There was a three-way tie for fourth among rookie Donna White, Sandra Spuzichand Jerilyn Britz, all at 217.