A lone Tamandani Nsaliwa strike seconds into the second half boosted AEK Athens FC's chances of progressing to the last 32 at the expense of FK Mladá Boleslav.
After failing to make their first-half domination pay, AEK went ahead moments after the restart when Nsaliwa converted Gustavo Manduca's cross. Although the hosts piled forward, they could not find an equaliser despite hitting the woodwork twice.
AEK started positively and were almost in front after just three minutes when Dániel Tõzsér's corner found Rivaldo but the Brazilian headed over. Mladá Boleslav responded quickly with Jan Rajnoch's drive just clearing Moretto's crossbar. However, AEK began to dominate with Rivaldo the central figure, and he forced Petr Pižanowski into a good save after a long-range effort. Meanwhile at the other end Alexandre Mendy tried his luck from distance, but the shot flashed wide.
The hosts then almost took the lead as Marek Matějovský's cross found the unmarked Jan Kysela, but he could only direct his header straight at Moretto. AEK hit back and Manú fired a presentable opportunity over the bar. Lorenzo Serra Ferrer brought Manduca on for Ismael Blanco at half-time and the substitution paid immediate dividends as the replacement found Nsaliwa who made no mistake with the finish.
Rivaldo came close to doubling the lead when his free-kick was tipped wide by Pižanowski. With ten minutes remaining, Milan Kopic's shot from distance looked to be creeping in, only for Moretto to palm the ball over. Four minutes later the home side came even closer to restoring parity when Radim Holub's shot hit the post seconds before Ivo Táborský tested the reflexes of Moretto once more. Mendy then struck the bar late on to compound a frustrating night for the hosts.