Villalibre scored his fifth goal of the summer and Sylla equalised in the final stages of the game
Athletic Club wrapped up pre-season with a 1-1 draw against Deportivo Alavés at Lezama on Saturday morning.
The Lions took the lead in the first half with an Asier Villalibre goal, his fifth of the summer, but Sylla equalised late on.
It was a very demanding match for the players who were not in the starting line-up for Friday night's clash with Real Sociedad in Barakaldo. Alavés had two clear first-half chances via Alkain and Miguel, but it was Villalibre who struck first.
The striker took advantage of some great build-up play between Unai Vencedor and Gorka Guruzeta, the latter swinging in a precise low cross behind the Alavés defence for the Buffalo to finish at the back post.
Villalibre had another chance at the start of the second half, narrowly striking wide with his unfavoured right foot.
Young winger Nico Serrano came off the bench and almost extended Athletic's lead with just his second touch of the game, hitting the crossbar with a powerful shot.
When the game seemed destined to finish 1-0, Alavés Mamadou Sylla scored after going through on one-on-one with Alex Padilla, punishing some defensive lapses brought on by fatigue.
Pre-season is now officially over and in nine days time Los Rojiblancos will host RCD Mallorca at San Mamés.