Borussia Dortmund manager Jurgen Klopp has said that his team "still have work to do" in their Champions League last-16 tie with Zenit St Petersburg.
The Germans will be the favourites to progress to the quarter-finals after a 4-2 win in the first leg, but Klopp is taking nothing for granted.
"We were close to an optimal performance tonight," UEFA.com quotes him as saying. "My team had its great moments, it was classy match, no doubt about that. But we are not through yet, we still have some work to do in the return leg."
Dortmund have won the Champions League once in their history and lost to Bayern Munich in the final last season.
