Flick's side, undefeated in 24 games across all competitions, are not taking Dortmund for granted despite carrying a 4-0 advantage into the return at Signal Iduna Park.

Dortmund host Eintracht Frankfurt later in the day and can go one point clear with a win, with five league matches remaining this season.

"We need at least one win against Chelsea. Obviously it is easier here with 80,000 to create euphoria. But we need two good performances and we will try to deliver," Terzic said.

Borussia Dortmund sporting director Sebastian Kehl on Wednesday said the club wants to hold onto English teen star Jude Bellingham "for a long time".

German police arrested a man on Friday who is suspected of planting explosives targeting the bus of soccer team Borussia Dortmund last week, the office of the German federal chief prosecutor said.

German investigators are looking into the possible involvement of Islamist militants or anti-Nazi activists in blasts that hit a bus carrying players from soccer club Borussia Dortmund, media reported on Wednesday.

German investigators hunted on Wednesday for possible suspects responsible for three explosions that rocked Dortmund football team's bus, injuring a player.

Borussia Dortmund earned a 1-0 victory over battling Ingolstadt with Bundesliga top scorer Pierre-Emerick Aubameyang grabbing his sixth goal in the last four league games to help them close in on second place on Friday.

Bayern Munich forward Robert Lewandowski scored a hat-trick as the Bundesliga leaders mercilessly obliterated Hamburg SV 8-0 on Saturday as coach Carlo Ancelotti celebrated his 1,000th game as manager.