Successive heartbreaks put Spain in danger of missing the quarter-finals in men's basketball at the Rio Olympics.
Successive late heartbreaks have Spain in danger of possible elimination from the Rio Olympics before they clear the group stage.
Brazil dealt the two-time defending silver medalists their second upset in three days on Tuesday when Marquinhos buried a tip-in layup with five seconds to play that gave the host nation a 66-65 win - their first of the 2016 Games.
Marquinhos, an NBA draft pick in 2006 who plays professionally in Brazil, finished with 10 points and five rebounds.
Four-time Olympian Pau Gasol struggled for Spain, shooting four-for-11 from the field for 13 points.
Elsewhere in the group stages, Lithuania topped Nigeria 89-80, and Argentina moved to 2-0 when it held on for a 90-82 victory over Croatia.
Brazil's women were not as fortunate, falling to Belarus 65-63. Australia stayed perfect with an 89-71 victory over France and Turkey defeated Japan 76-62 to pick up their first win.
HIGHLIGHT OF THE DAY
Marquinhos' winner came off a put-back of a missed jumper by Marcelo Huertas. Spain had a chance to respond on the ensuing possession, but Sergio Llull's desperation jumper fell harmlessly to the floor.
MVP OF THE DAY
Turkey's LaToya Sanders poured in a Rio-high 36 points (14-for-18 from the field) and added seven rebounds and two blocks for good measure.
QUOTES OF THE DAY
"I'm very confident this situation will end with the next game. ... I will call it [the situation] challenging, not bad, but challenging. It's not bad until you're out, and we're still very in," - Spain coach Sergio Scariolo staying upbeat.
"It was a unique moment playing at home, at my home, in my city. All I wanted was to be in that moment. Every player, when he dreams about becoming a player thinks, 'I wonder if I will ever be the decisive player in a game', in a free throw or in a three-point shot. It was my big moment. That is [usually] not part of my game, I am not a guy who has a lot of points in rebounding, neither offensively nor defensively. But that was my moment and I embraced it," - Marquinhos on his game-winning shot.
In a potential preview of the men's gold medal game, the United States face their toughest test yet in Australia after two blowouts to open the tournament. Group A continues with Serbia against France and Venezuela taking on China. For the women, USA meet Serbia among three matches.