Leverkusen were below their best but did just enough to qualify after last week's comfortable first-leg win in Greece.

It was the first time Leverkusen made it through a two-legged Champions League knockout tie since they reached the final in 2002, when they lost 2-1 to Real Madrid.

The 2024 German double winners will face either Premier League leaders Arsenal or German champions Bayern Munich, who eliminated Leverkusen at the last 16 stage last season.

"The game didn't go at all like we'd imagined. Too sluggish -- really the only positive is that we kept a clean sheet and we're through to the next round," a frustrated Leverkusen captain Robert Andrich told Amazon Prime.

"We needed more speed, more bite, both against the ball and with it -- thankfully the opponent didn't punish us."

Echoing his captain, Leverkusen midfielder Jonas Hofmann said coach Kasper Hjulmand "will probably go home and drink a beer out of frustration to wash down that performance. There's nobody here who can be satisfied with that".

Leverkusen had not conceded at home in any competition since early January and were rarely troubled by the energetic but toothless Greek champions.

Olympiacos rested six starters in their Greek Super League match on Saturday in the hopes of reaching the Champions League last 16 for the first time since 2013-14, when they were narrowly eliminated by Manchester United.

Seeking to give his troops a little extra motivation, billionaire Olympiacos owner Evangelos Marinakis -- who also owns Nottingham Forest -- promised an "unprecedented" financial bonus for reaching the last 16.

Patrik Schick scored twice in three minutes in last week's opening leg and the Czech striker was in the thick of things early on, heading just wide and dragging a lob over goalkeeper Konstantinos Tzolakis but past the far post inside six minutes.

After that early flurry, Leverkusen were content to sit back as the match wore on, forcing the visitors to try and create something.

Leverkusen's best chance of the match came midway through the second half when Alejandro Grimaldo blasted a shot against the crossbar with Tzolakis beaten.

Right-back Lucas Vazquez, a Champions League winner with Real Madrid, limped off late in the second half in the only black mark for the hosts.