Xabi Alonso wants Bayer Leverkusen to click through the gears after they edged out Jena in the DFB-Pokal. (More Football News)
Jonas Hofmann's header was enough to send holders Leverkusen into the next round with a 1-0 win on Wednesday.
Alonso's side only allowed their lower-league opponents to have six shots, but worryingly for the Bundesliga champions, those did accumulate to 1.04 expected goals (xG).
Indeed, Hamza Muqaj missed a golden opportunity for the hosts worth 0.75 xG in second-half stoppage time.
With RB Leipzig next up in the league, Alonso knows his team have to sharpen up.
"[We faced] a good opponent and it wasn't easy," said Alonso.
"We have to work on a few things, but we are in the next round and that's what counts. Now we go straight into preparing for the next league game."
Leverkusen did bolster their defensive options, though with the signing of Nordi Mukiele.
The versatile defender has joined on loan from Paris Saint-Germain, and could be in line to make his debut against his former club Leipzig on Saturday.
Odilon Kossounou, meanwhile, has left Leverkusen to sign for Atalanta, who beat Alonso's team in last season's Europa League final, on loan.
