Oriente Petrolero's six-match winning run came to an end with a 1-0 loss at Nacional Potosi, and Xabier Azkargorta's Bolivar capitalised.
Maygua scored a hat-trick to guide Bolivar to a resounding 5-1 home win against struggling Sport Boys.
Bolivar are just three points adrift of top spot and have a game in hand on Oriente Petrolero, who have five to play.
Maygua was the star against Sport Boys at the Estadio Hernando Siles in La Paz.
He opened the scoring in the 11th minute, controlling a corner before curling a 30-yard effort into the bottom corner.
Maygua's second on the half-hour mark was similarly good, half-volleying into the same bottom corner from 25 yards.
He went into the area to complete his hat-trick in the 51st minute as he headed in to make it 3-0.
Carlos Tenorio scored in a one-on-one and Juan Arce scrambled in before Marcos Ovejero's late consolation.
At the Estadio Victor Agustin Ugarte in Potosi, hosts Nacional claimed a 1-0 win over Oriente Petrolero.
Gery Garcia Guzman's 92nd-minute cross-cum-shot found the back of the net.
Wilstermann are alongside Bolivar on 30 points after Carlos Vargas' 84th-minute goal saw them beat Real Potosi 1-0 in a match that featured three red cards.
Elsewhere, The Strongest edged Blooming 1-0 and San Jose overcame Universitario Cobija 2-1.
