Goals either side of the break from Hector Gaitan and Leandro Ferreira gave Boys the victory at the Estadio Samuel Vaca Jimenez in Warnes.
Club Universitario had the chance to match Sport Boys on 13 points, but were held 1-1 on the road at Wilstermann.
Ruben Cuesta gave Universitario the perfect start just two minutes in, but their lead was nullified on the half-hour mark by Wilstermann's Ignacio Garcia.
San Jose made it three wins on the spin, beating Oriente Petrolero 2-0 at home.
Marcelo Gomes struck a six-minute brace early in the second half at the Estadio Jesus Bermudez in Oruro, and it was enough for the hosts.
Real Potosi are third on 10 points, and remain the only unbeaten side in the league, after conceding twice late in a 3-3 draw with Aurora.
Potosi led 3-1 with five minutes of normal time to play after an Ivan Zerda brace in the second half had broken the game open for the hosts.
But Oscar Diaz's second goal of the game, followed by Rodrigo Borda's 89th-minute equaliser, ensured second bottom Aurora of a point and denied Potosi the chance to go second in the table.
