Dennis Conner won the America's Cup a third time Friday, routing New Zealand by more than 21 minutes and setting the stage for the yachting battle to return to the courtroom where it has mainly been contested.

After losing the lead briefly on the first leg of the triangular course, Conner used his catamaran's superior speed to leave the monohull New Zealand miles behind and turn back the Kiwi's challenge in three hours, 27 minutes and 38 seconds. New Zeaands monohull finished 21:10 later.

Yachting's most prestigious trophy will remain in the hands of the San Diego Yacht Club unless New Zealand's expected legal challenge to Stars & Stripes is upheld by a Manhattan judge.

There was no evidence of American "sandbagging," or making the race appear closer than it actually was. Conner enjoyed stronger winds and a more favorable course than Wednesday, when Stars & Stripes won the opening race of the best-of-three series by 18:15.

Conner rounded the first turn with a 10-minute lead over New Zealand after the 13-mile upwind beat and increased the advantage by 1:56 on the second leg. The race began into westerly winds of six knots that shifted slightly to the north as the yachts closed in on the first mark. The wind shift turned a tacking duel into more of a reach and the second leg into more of a downwind run.

Catamarans are especially fast on the reach and Stars & Stripes slashed around the mark into the second leg exactly 10 minutes ahead of New Zealand with 15 knots of wind pushing the wing-like sail.

The New Zealanders took the lead briefly in the early stages of the race with a clever false tack that the veteran Conner took.

As happened at the races in Australia last year, when Conner reclaimed the Cup after losing it, superior boat speed allowed the American to recapture the lead about 12 minutes into the contest. Both boats started behind the line in six-knot winds from the west.

There were whoops and cheers at the San Diego Yacht Club, where the "Grand Auld Mug" will remain until 1991, when the next cup defense is planned, or until New York Supreme Court Justice C. Beauchamp Ciparick rules on New Zealand's expected protest.

The next cup defense should be a bit more orderly now that a new set of guidelines for the regattas has been established. Under the terms of the agreement signed Wednesday in San Diego, challenges will be accepted for 60 days with no one considered the first challenger, who could legally insist on an exclusive series with San Diego.

The challengers will decide when the next cup will be sailed and in what type of boat. They will then seek San Diego's agreement to the terms.