League leaders Bolivar edged Wilstermann 1-0 on Sunday, while rivals Oriente accounted for second-bottom Sport Boys 3-0 on the same day.
The results left Bolivar (43 points, plus 26 goal difference) one point clear of Oriente (42, plus 16) heading into the 22nd and final round.
Bolivar - unbeaten in five matches prior to kick-off - only needed a 26th-minute strike from defender Ronald Eguino at the Estadio Hernando Siles.
Oriente's win was more straightforward as they disposed of lowly Sport Boys at the Estadio Ramon Aguilera Costas.
Two first-half goals from Alcides Pena and Yasmani Duk set the tone in Santa Cruz.
Duk netted his second in the final minute of normal time as Oriente won their third consecutive match.
Club Universitario come from two goals down to beat The Strongest 3-2 at the Estadio Olimpico Patria, with Argentinean striker Martin Palavicini bagging a hat-trick in the final 10 minutes.
The Strongest - third in the standings - were seemingly in control on the hour-mark thanks to goals from Pablo Escobar and Victor Melgar.
But Palavicini led Club Universitario's remarkable comeback, starting in the 80th minute.
Palavicini pulled another goal back from the spot in the 85th minute before netting a dramatic equaliser four minutes later.
In other results, Nacional Potosi survived a late rally from cellar-dwellers Universitario Cobija to win 3-2.
Petrolero Yacuiba saw off Real Potosi 2-0, while San Jose defeated Blooming by the same scoreline.
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