Daniel Farias' Tachira are suddenly on a four-match winless run in all competitions after a 1-0 loss at home to Metropolitanos.
Jorge Rojas' 17th-minute goal was all the visitors to the Estadio Polideportivo de Pueblo Nuevo needed to claim an upset win.
It meant Deportivo La Guaira's 0-0 draw at Deportivo Petare was enough to see them climb a point clear at the top.
Only one team remain unbeaten – Carabobo – and they edged past Zamora 2-1 for just their third win in 11 league matches this season.
Victor Perez opened the scoring in the ninth minute for a team that has drawn eight outings this campaign.
It looked like a ninth draw was on the cards when Johan Arenas levelled for the winless visitors, but Gustavo Gonzalez scored a 64th-minute winner.
Third-placed Tucanes saw their winless run in the league extend to three matches, held to a 0-0 draw by Aragua.
Caracas, who sit fifth but have played three fewer games than the teams above them, suffered a 1-0 loss at Deportivo Anzoategui after Edwin Aguilar's second-half penalty.
Zulia and Mineros de Guayana played out a 1-1 draw, while Portuguesa came from behind to earn a 2-2 result at home to Trujillanos.
Estudiantes de Merida claimed a 2-0 win at Llaneros de Guanare and Deportivo Lara battled to earn a 2-2 result at Atletico Venezuela.
