Dennis Conner's Stars & Stripes dodged another potential death blow today, beating the best boat in the America's Cup fleet, AmericaOne, by 22 seconds to stay alive in a two-way battle for the last spot in challenger finals.

AmericaOne's crew put up a respectable effort after changing the boat overnight to a new, secret underwater configuration that looked like a step backward in winds that dropped from a bracing 18 knots at the start to 10 at the finish.

Speculation centered on experimental changes to the rudder or keel of AmericaOne, or both. Skipper Paul Cayard wouldn't say, but it made no matter as the fleet leader, its spot in the challenger finals already ensured, had little incentive to push hard and never led in the race, closing the gap at the end as the wind dropped but never threatening to overtake.

Stars & Stripes' victory, coupled with the Italian boat Prada's win over Nippon, set the stage for a sudden-death showdown between the two Saturday for the No. 2 spot in the two-boat challenger finals. Stars & Stripes needs one more victory to force the race-off, and rumors were swirling that Prada may be planning a legal challenge to stop Conner's charge before the showdown occurs.

Cayard locked up the top spot in challenger finals Wednesday with an 8-1 record over the first nine races.

Today, he considered not racing at all, simply handing the win to Stars & Stripes, but opted to make an appearance for the good of the Cup.

"You know I'm always preaching about making the America's Cup better," he said, "so I thought I'd better back up my ideas. At home last night it all came clear to me. I told both skippers we'd race hard today."

Prada won handily, beating Nippon in a race that was nip and tuck till the halfway point, when a halyard stuck and Nippon's crew was unable to take the headsail down and sailed downwind with a jib in the way of the spinnaker.

The win left Prada at 7-3 after 10 races and Stars & Stripes with six points after nine. Stars & Stripes has one race to go--a makeup against America True on Friday for a race that was postponed for repairs to Stars & Stripes after a collision.

If Stars & Stripes wins Friday, it will be tied with Prada and the two will square off for a spot in the best-of-nine challenger finals, starting Jan. 25.

That scenario now seems likely, but Cup skulduggery may intervene. Prada syndicate chief Patrizio Bertelli spent more than $50 million and 2 1/2 years getting this far and has shown intense distaste at the prospect of being knocked out of the field by an upstart, $10 million, one-boat team that didn't even start practicing till September.

Bertelli is said by sources in his camp to be prepared to file a protest against Stars & Stripes, saying its improved performance this round was largely because of a new mainsail built using technology borrowed from the New York Yacht Club's Young America Syndicate, which didn't make the semifinals.

Cup rules ban challengers from sharing technology. Prada's protest, if filed, would ask that Stars & Stripes be disqualified for using illegal gear.

Stars & Stripes jib trimmer and operations chief Bill Trenkle discounted the potential protest.

"We're obviously not going to purposely break the rules, and we know the rules," he said. "It's very clear--you can't use other team's gear."

He did say that Stars & Stripes tried to copy every good idea it saw. "We had to, with our budget," said Trenkle. "But we absolutely built that sail ourselves."

The 57-year-old Conner, with eight Cup campaigns under his belt including four wins, has turned the sailing over to younger people but is still calling the shots ashore and his reputation for unsinkability perseveres.

"We feel like we've been in a gunfight every race," tactician Tom Whidden said after today's victory. "You know Dennis--he never does anything the easy way. We've had our backs to the wall so long, it feels like the wall is moving."