The Červenobílí were fearless during the early stages with Simion Michez’s deflected strike forcing Julen Agirrezabala into a brilliant save inside seven minutes. Trouble was caused from the ensuing corner but Mojmír Chytil’s header was more routine for the home goalkeeper.
El Hadji Malick Diouf then headed marginally wide and Dani Vivian sustained a cut to the eye as Athletic finally got a break for the unrelenting pressure being faced.
The Lehoiak gained a greater foothold when the action resumed but still couldn’t trouble Antonín Kinský in the Slavia goal and Michez once again worked Agirrezabala, this time with a header.
The hosts thought they had their chance for a breakthrough from the penalty spot when Jan Bořil challenged Iñaki Williams shortly before the half-hour mark, although the decision was overturned due to Gorka Guruzeta barging Oscar Dorley before that.
Even so, Nico Williams had looked bright whenever he had possession and the winger’s strike took a deflection off David Zima that completely wrongfooted Kinský for the opener.
Lukáš Provod and Michez still tested Agirrezabala before the break as a reminder that Slavia weren’t out of the game yet, a message that was reaffirmed after the restart with a venomous Michez strike forcing another eye-catching save from the Spaniard.
Christos Zafeiris then played a searching pass for Ondřej Zmrzlý, who could only fire into the side netting on the stretch before substitute Tomáš Chorý was unable to find the target from two attempts and then saw a header saved.
The home goalkeeper’s heroics meant that, even with Iñaki’s pass being intercepted after Kinský had rushed out of his goal, Athletic took all three points and continued their unbeaten start to the UEL campaign, having also lost just one of their last nine across all competitions.
In doing so, they inflicted just the second defeat in Slavia’s 18 competitive matches this term – the other came against LOSC Lille in UEFA Champions League qualifying.