Chile's Ricardo Acuna upset Juan Farrow of Los Angeles, 6-3, 6-3, in the singles final and then teamed with Paul Groth to win the doubles title in the Michelob Light Masters tennis tournament yesterday at Rock Creek Stadium.

Groth, from Decatur, Ga., and Acuna defeated Armand Molino of Hollywood, Fla., and Mike Davidson, of Milwaukee, in straight sets, 6-4, 6-3.

The ninth-seeded Acuna, whose singles victory pushed him to fourth in the final point standings for this segment of the U.S. Tennis Association Circuit, won $1,300 for his 80 minutes of work in the singles final and another $700 for winning the doubles.

In the process, he deprived Farrow of first place in the tour's singles standings and the accompanying 30 world ranking points. Had he won, Farrow would have passed Bruce Foxworth of St. Louis by one point. But he finished second in the circuit standings, ahead of Jeff Simpson of New Zealand. Acuna expects his fourth-place finish in this part of the tour to propel him from 175th to near 120th in the world rankings.

Acuna, who upset the top-seeded Foxworth and sixth-seeded Ben Testerman in advancing to the final, abandoned his usually flashy game yesterday and patiently waited for Farrow to hit the ball long or into the net.

"He was missing an awful lot of balls, and I decided to just hit the ball back to him and let him miss," said Acuna, who had reached the semifinals only once in his last five tournaments. "I didn't want to try anything fancy. It was obvious he was worrying and felt the pressure, so I didn't have to do anything.

"He was very inconsistent. Why should I attack this guy when he isn't hitting the ball in?"

Farrow became unsettled early in the first set, when he fell behind, 4-1, before he could bring his serve under control. He managed to hold serve only once in the first set, getting fewer than 40 percent of his first serves in.

In the last game, Farrow led, 40-15, before Acuna pushed him to deuce and eventually broke his serve.

Farrow, behind a powerful serve, stayed even with Acuna in the second set until the Chilean disarmed him with a series of lobs and offspeed shots.

After he tied the set at 3-3, Farrow lost the next three games. In the last game, he didn't score a point.

Farrow had begun the day by finishing off Bill Csipkay, of Wykoff, N.J., in a match that had been suspended Saturday because of rain. Farrow, who had won the first set, lost the second and was leading, 2-0, in the third, dropped two straight games before rebounding to win the last set, 6-2.