Selenski drove past defender Louise Cavenaile and tried to cross the ball to Shannon Taylor at the far post. Belgium goalkeeper Aisling D'Hooghe got in the way of the play, but Selenski swatted at the ankle-high clearing attempt and roofed into the top corner of the far side of the goal to give the Americans the lead.
The United States finished last among the 12 teams at the tournament, its worst showing in history.
"We have finished where we deserved to," Rachel Dawson, a graduate of Eastern High, said. "We just didn't take our chances in this tournament so 12th place is what we go home with. It's been a humbling experience for us all. Humility gives you the desire to work harder and teaches you the discipline to execute better games. We've done an OK job here, but we know we can be better."
"It's been so close every game, but not gone our way," Katie O'Donnell, a Wissahickon graduate, noted. "In our games against opponents ranked higher than us, we took it to them and kind of shocked the world."
"We have amazing kids coming up," Keli Smith-Puzo said. "The young talent is going to be amazing. I think Rio 2016 is going to be a completely different team."
The Netherlands retained the women's Olympic title with a 2-0 win over world champion Argentina at Riverbank Arena. Netherlands will try for the first-ever Olympic double when the country's men's hockey team takes on Germany on Saturday.
Tae kwon do. South Korea's Hwang Kyung-seon defended her Olympic title in the women's 67-kilogram division, and Sebastian Crismanich of Argentina won the gold medal in the men's 80-kg category.
The bronze medals were won by Paige McPherson of the United States and Germany's Helena Fromm.
Five-time world champion American Steven Lopez lost his opening bout in the men's competition. Two members of his family said later that he had a broken leg.
Track and field. Tatyana Lysenko of Russia set an Olympic record of 77.56 meters (254 feet, 5 inches) with her first attempt and then improved it with her fifth at 78.18 (256-6).
Aksana Miankova set the old mark of 76.34 (250-5) in Beijing.
Anita Wlodarczyk of Poland earned the silver at 77.60 (254-7), and the bronze is still in dispute.
Renaud Lavillenie of France won the pole vault gold medal with an Olympic record jump of 5.97 (19-7).
Sailing. Australia's Mathew Belcher and Malcolm Page, and New Zealand's Jo Aleh and Olivia Powrie won the 470 class gold medals by overwhelming their British rivals on Weymouth Bay.
The Americans failed to win an Olympic sailing medal for the first time since 1936.
Elsewhere. Park Chu-young scored to lead South Korea to a 2-0 victory over Japan and a bronze medal in men's soccer. Brazil and Mexico play in the gold-medal match Saturday at Wembley Stadium. . . . Brazil and Russia advanced to Sunday's men's volleyball final. . . . Italy upset Serbia, 9-7, to advance to the men's water polo final against undefeated Croatia, which beat Montenegro, 7-5, in the other semi. . . . Defending champion France will take on Sweden in the men's handball final Sunday. . . . Dzhamal Otarsultanov won the men's 55-kg freestyle category, beating Vladimer Khinchegashvili of Georgia to give the Russians four wrestling golds, tops for any nation.