Luna Rossa sailed its 72-foot catamaran with duct tape holding together its main sail after a pre-race mishap, but still finished nearly two minutes ahead of Artemis.
It was nonetheless still something of a victory for Artemis, which suffered a fatal training accident in May and whose participation in the event was in doubt until recently.
Unable to train until two weeks ago, Artemis is the clear underdog in a three-way competition with Italy and New Zealand for the right to compete against defending champion Oracle Team USA for the fabled America's Cup.
A small crowd that met the boats at the finish line along the San Francisco waterfront waved a few Italian flags for Luna Russa - and heartily cheered for Artemis.
"Just to be out there leading them to mark one after all we've been through was enough to put a smile on my face for a long time," Artemis skipper Iain Percy said after the race.
The Swedish team showed that it remains a contender, beating Italy at the starting line and finishing closer to its opponent than Luna Rossa had finished in an initial series against Emirates Team New Zealand.
Artemis finished one minute and 57 seconds behind Luna Rossa on Tuesday. The closest the Italians came to Team New Zealand in the first set of races was two minutes and 19 seconds.
"The last month's been hard, and it was good for us to finish today with a win," said Luna Rossa helmsman Chris Draper, who added they had torn the main sail just before the start of the race and the shore crew was still taping it together with only three minutes to go.
The tear "made sailing the boat a little bit harder trying to nurse it," he said.
The winner of the best-of-four semi-finals between Artemis and Luna Rossa will compete against New Zealand, which defeated Luna Rossa in a round-robin preliminary series, for a spot in the main event against Oracle beginning September 7.
Software billionaire Larry Ellison's Oracle team won the Cup in 2010 and with it the right to set the rules and choose the venue for this year's competition.
His decision to use high-tech catamarans that can reach speeds of more than 50 miles per hour on windy San Francisco Bay has been much-criticized in light of the Artemis accident in May, in which British Olympic gold medallist Andrew "Bart" Simpson was killed after he was trapped under a capsized Artemis boat.
Before Tuesdays race, Artemis CEO Paul Cayard talked to Reuters about the teams difficulties.
"We've had our challenges," he said. "But challenges are just an opportunity, an opportunity to be together, work together and overcome, and ultimately that's what being on a team is all about. It's also more opportunities to build that strong relationship.
"I feel that Artemis is a strong team because of what we've been through and were taking it on the race course."
Artemis skipper Iain Percy described getting back on the boat and into the race as bittersweet.
Simpson and Percy had been friends since they were 10 years old, and went through Britain's youth sailing program and then on the Olympics together.
Late last month, when Percy was about to step into the yacht for the first time since Simpson's death, his voice choked with emotion.
"It's really a sad day for me personally," he said. "I'd love to be going out there with Bart. He would have been so excited."
He looked at a ribbon with Simpson's nickname printed on the sleeve of his wetsuit.
"He's gonna be with us out there," he said. "So keep an eye on us Bart."