It was no easy task to find John Sadri on the computer list of the Association of Tennis Professionals a year ago. You either had to know him or love him, because your eyes needed three days off by the time they located his name. He was 414th in the rankings, little place to go but up.

Since then, he's gone up, up and away. He is 20th on the latest list, a jump that requires a calculator to determine its improvement. Few of his colleagues have traveled so far so fast.

"Two big things happened," the former North Carolina State All-America said yesterday afternoon after edging Tomaz Smid, 6-4, 6-4, in a first-round match in the $125,000 Volvo Tennis Classic at George Washington University's Smith Center.

Joining Sadri in the second round were Ferdi Taygan, who stopped Hank Pfister, 6-4, 6-4; Andrew Pattison, who produced a mild upset with his 6-2, 6-4 victory over Dick Stockton, and Rod Frawley, who nipped Rick Meyer, a late placement for John Austin, 6-4, 5-7, 6-3. Taygan and Brian Teacher advanced to the second round of the doubles with a 6-3, 6-3 triumph over Anand Amritraj and Pattison.

Last night, third-seeded Eddie Dibbs was pushed to the limit by Sherwood Stewart before winning, 7-6, 4-6, 6-4, in a tense, 1-hour 45-minute struggle. Accompanying him to the second round was No. 7 seed Ivan Lendl, who dominated Billy Martin during a 6-2, 6-1 triumph.

"I started playing doubles with Tim Wilkison," Sadri continued, "and we were making the quarters and semis every week. That meant about 1,000 extra volleys for me. I had always had trouble with them, because I never had to hit them in college. There, nobody could return my serve. But I started to get more confident at net and I think that helped my overall game. It meant I had something besides my big serve. I'd always had that."

Make it BIG SERVE.When it was last timed, nine months ago, it was going 130 miles per hour. Last week, it produced 51 aces in four matches, earning its owner a $2,000 Persian rug. But until five months ago, it was all show and no go.

"I just felt a change when I went on the Asian circuit last fall," Sadri said. "I'm not sure exactly what happened. I just know my game started to come together. I got more confidence in my ground strokes, and I wasn't afraid to stay back and rally with guys from the baseline.

"When I wasn't worried anymore about who I was playing, I'd gotten enough experience so nothing took me by surprise. I didn't think about where it was (John) McEnroe or (Jimmy) Connors or (Guillermo) Vilas. I started to think about winning."

He lost the 1978 NCAA final to McEnroe in four sets, three of which went to tie-breakers. He's zero for three against him, and has yet to beat Connors, Bjorn Borg or Vilas.

Dibbs was always in trouble.

"He served very well. It's the best he's played in a while," Dibbs said afterward. "I usually return well, but he was hitting the corners all the time. The match was really close, and I never felt as though I had control."

He had the next best thing, though. After Stewart came back from 15-40 to hold serve in the seventh game of the first set, he broke Dibbs to tie the set, 4-4. Both players then held to 6-all. When Stewart took a 3-1 lead in the tie breaker, he appeared to have taken command.

So much for appearances. Dibbs won six of the next seven points to capture the set, but lost his momentum by allowing Stewart to break serve in the next game. The 33-year-old Texan, the world's leading doubles player last year, made the break stand up and evened the match.

"If he'd gotten a quick break in the third," Dibbs admitted, "and gotten right on top of me, he probably would have won. I was trying to make him earn points on my serve and not make mistakes on his."

He practiced his strategy well. With Dibbs leading, 5-4, Stewart double-faulted twice, eventually came back to 30-40, then watched his chances disappear when Dibbs backhanded a lob over his head.

"Those double faults really helped me out," Dibbs conceded. "The way I was going, I was hoping he'd do it twice more." Stewart didn't have to.