Pablo Salinas' brace cancelled out Gualberto Mojica's first-half double for visitors Oriente to Santa Cruz de la Sierra, before Martin Minadevino struck the winner in the third minute of injury time.
Oriente were on track to regain their league lead - lost when Bolivar won earlier on Sunday - as they were 2-1 up heading into the dying stages.
But Salinas' second in the 85th minute, combined with Minadevino's winner, saw Eduardo Villegas' men slump to consecutive defeats - and fall second in the table on goal difference to Bolivar, with both on 33 points.
Bolivar were 2-1 winners at home to Club Universitario, Carlos Tenorio and Juanmi Callejon scoring for the new league leaders.
Xabier Azkargorta's Bolivar take on form team The Strongest on Wednesday, after the latter won for a third straight time - downing cellar-dwellers Universitario Cobija 3-1 away from home.
The Strongest sit fifth on 27 points, shy of Wilstermann (third, 30) and San Jose (fourth, 28).
Wilstermann conceded twice in six minutes in the second half to lose 2-1 to second-bottom Sport Boys, who moved six points clear of Cobija.
San Jose twice coughed up a lead at home to Real Potosi, before storming to a 6-2 victory to climb above their opponents in the table.
Real Potosi's loss left them in seventh on 26 points, behind last-gasp winners Blooming in sixth (27).
Gaston Mealla's brace inside the final 20 minutes helped Nacional Potosi to a 3-1 win over Petrolero Yacuiba, as they claimed ninth spot on goal difference from the side they conquered with both on 22 points.