Veteran 12-meter skipper Bill Ficker called it the best America's Cup race "in many, many years," but even that high praise didn't do justice to today's showdown on Rhode Island Sound.

Through 20 miles in the opening race of the 25th cup challenge, there was barely a boat length between American defender Liberty and foreign challenger Australia II. No one can be sure how this race would have ended if a steering fitting hadn't collapsed on Australia then, throwing her crew into brief and decisive chaos.

Liberty quickly took the lead as the Australians scrambled to jury-rig a repair around the broken pulley. Four miles later Liberty finished 1 minute 10 seconds ahead for a 1-0 lead in the best-of-seven final series for yachting's most prestigious prize.

But that result hardly reflects the startling competitive evenness of these yachts, which had not faced each other before.

Today's racing, said Liberty sail trimmer John Marshall, proves that "this ain't no party, this ain't no disco, this ain't no fooling around."

And a recounting of the events bears him out. Australia won the start by a hair's breadth--three seconds--but Liberty stole the lead as they battled upwind in a cool and perfect sailing breeze of 18 knots. Australia promptly fought back and led by a boat length or two as the yachts sped around the first two of five marker buoys on the 24.3-mile race course.

Many U.S. observers were shaken by the Australians' ability to cling to the advantage in the kind of fresh winds in which Liberty was supposed to be strongest. But with 7 1/2 miles gone, the burgundy red Liberty bore down over Australia and again recaptured the lead.

Liberty skipper Dennis Conner said the lead change was simply a result of better boat speed on the reaching point of sail, when the wind is across the beam. But he is a tenacious lead-holder and expanded the edge through the next two legs. Liberty was 28 seconds ahead when the two boats turned their backs to the wind to begin the next-to-last leg of the race.

Australia selected a light spinnaker and when the breeze moderated slightly she streaked back into contention. "We were visibly losing," said Marshall. When the two boats came together nearing the final turning mark on the course they were side by side, with neither having a discernible advantage.

For such wildly disparate yachts--Australia with her radical winged keel and Liberty with her heavier, traditional hull design--to be so close after so long was a circumstance few expected.

So it came down to tactics and in the end it came down to a bad pulley.

Conner made an aggressive right-hand turn and bore down on Australia, carrying with him the right of way and the intention of taking the inside track to the final mark.

The move appeared to startle Australia skipper John Bertrand. With 30 yards separating the boats he swung the wheel to avoid collision, but the steering pulley gave way, the boat broached and the race was all but history. Forty-five uneventful minutes later, it was history.

"But they were fast," said Liberty tactician Tom Whidden, "a lot faster than we thought they'd be."

Australian syndicate chief Alan Bond was asked how badly the gear breakdown affected his yacht's performance. "We took the time that the pulley was out of order and compared our speed while we were repairing it against what we should have been making," he said slyly. "The difference came out to 1 minute 22 seconds."

"It was unfortunate," said skipper Bertrand, "because it was obvious it was going to be a very close race right to the finish."

And the U.S. crewmen were in accord.

"Australia is obviously not slow in a breeze," said Conner. "She's obviously not slow downwind and I was impressed with her ability to turn. The breaks went our way today and we won, but they could have gone the other way."

"The boats apparently are very even," added Liberty designer Johan Valentijn, who was among the leaders of summer-long efforts by the host New York Yacht Club to have Australia II penalized or disqualified from racing on grounds her secret winged keel gave her an unfair advantage.

The advantage was thought to be in light air and smooth seas, but Australia II proved today she can race in a blow. Theories about her purported ponderousness on downwind legs were knocked into a cocked hat when she nearly slid by Liberty on the downwind leg.

Only one theory about this cup and these boats still seems to hold water: that a crucial factor in deciding a winner will be the preparation and race-readiness of the crews and the yachts.

"Today showed us that the one who makes the least mistakes will win the event," said Bond.

The Australians expected to work about four hours tonight repairing the broken pulley and strengthening three other steering pulleys so the same thing won't happen again. Racing resumes Thursday at noon, with clear skies and 10- to 20-knot northerly breezes expected.