Manchester City director of football Txiki Begiristain believes Schalke pose a threat if the Premier League champions allow the last-16 Champions League tie to be played on their opponents' terms.
Pep Guardiola's side were rewarded for winning their group with a trip to Gelsenkirchen in the first leg on February 20 – one of three Bundesliga-versus-Premier League ties after Liverpool and Tottenham were paired with Bayern Munich and Borussia Dortmund respectively.
Second in Germany's top flight last season, Schalke have struggled domestically this time around having lost star midfielder Leon Goretzka to Bayern and are languishing in 13th.
But, following a pair of tightly contested 2-1 wins over Hoffenheim in the group stage, former Barcelona winger Begiristain does not believe City's next steps in the Champions League against German opponents will necessarily be straightforward.
"The German clubs are very strong with that box-to-box game. We have to be very good in the boxes," he told BT Sport.
"If we run, they are going to win. We have to keep control of the ball and the rhythm of the game
"If we start running box-to-box, in that they are the best."
A Premier League title race with Liverpool that threatens to go to the wire could distract City in their question for European glory, although Begiristain is keen for them to improve upon a solitary semi-final appearance from the 2015-16 season.
"For us, always the Premier League is very important, it is a dream for Manchester City to go through [in the Champions League]," he added.
"We were once in the semi-finals and we want to be close."
