Uruguay are all but out of the Copa America Centenario after suffering a shock 1-0 defeat to Venezuela, as star forward Luis Suarez was unused.
A first-half goal from Salomon Rondon was enough for the Venezuelans, which edges them closer to a quarter-final berth.
The result moves Venezuela to first in Group C on six points, while Uruguay sit last without a point from their first two games.
A Mexico draw with Jamaica will confirm Uruguay's exit from the special-edition centenary tournament, and also seal Venezuela's progression to the last eight.
The second-half of the contest was marred with confusion as Suarez warmed up but had not been named in the line-up.
However, the Barcelona star did not feature, and was not shy in expressing his frustrations with the Uruguay coaching staff.
Uruguay coach Oscar Tabarez made four changes to the starting line-up from their 3-1 loss to Mexico, bringing in Cristhian Stuani, Gaston Ramirez, Alvaro Gonzalez and Gaston Silva for Diego Rolan, Nicolas Lodeiro, Matias Vecino and Alvaro Pereira.
Venezuela's Rafael Dudamel made just the one change to his side that beat Jamaica 1-0, replacing Luis Seijas with Adalberto Penaranda, and they started the brighter of the two sides.
While Venezuela pressed forward early and put the Uruguay defence under pressure, they found it difficult to create any clear-cut opportunities on goal.
Uruguay had a good chance to open the scoring in the 15th minute through Edinson Cavani after Gonzalez set him up with a cutback, but the Paris Saint-Germain forward fluffed his shot.
Cavani came close again just past the half-hour mark when he looked set to get on the end of a Ramirez free-kick, but he was unable to get any connection on the ball as it went off the post and out for a goal-kick.
However, it was Venezuela who took the lead in the 36th minute, with a goal that came out of absolutely nothing.
Alejandro Guerra broke down the right and spotted Uruguay goalkeeper Fernando Muslera off his line, and while the Galatasaray man made a good save to tip the ball onto the bar, Rondon reacted quickest to convert the rebound.
Tabarez made no changes at half-time as Uruguay looked to turn things around, and an early free-kick was blasted into the wall by Cavani.
The Salto-born forward then played a ball in for Stuani who laid it off for Ramirez, but the former Southampton man's first-time shot went well wide of the goal.
Stuani came close to equalising in the 52nd minute with a shot on the turn, but his effort went just over the crossbar, to the relief of Venezuela goalkeeper Daniel Hernandez.
Cavani had shouts for a penalty waved away and Venezuela almost made it 2-0 seconds later on a counter-attack, but Muslera made a great save from Penaranda one-on-one.
Tabarez made all three substitutes in the closing stages as they looked to find an equaliser, and came closest through Cavani.
The 29 year-old was straight through on goal but somehow completely missed the target, while second-half substitute Romulo Otero missed an open goal for Venezuela in the dying stages, but it mattered little as they held on for the slender victory.