Borussia Dortmund head coach Marco Rose admitted he fears the worst after Giovanni Reyna came off injured during the victory over Borussia Monchengladbach.

Rose's side remained within six points of Bundesliga leaders Bayern Munich following a comprehensive 6-0 rout at Signal Iduna Park.

Marco Reus produced a man-of-the-match display for the hosts; becoming their first player in over five years to register five direct goal involvements in a single German top-flight game (two goals, three assists).

However, the victory was marred by an injury to Reyna, who limped off just 27 minutes into his first start since August.

Leaving the pitch in tears, the United States international had only recently returned from a hamstring injury sustained while on duty with the Stars and Stripes five months ago.

While the extent of the damage is yet to be revealed, Rose is fearful for the 19-year-old.

"You have to assume that something has broken open again in the previous place," the head coach said.

"A fit Gio would have been important for us. He's just coming off a long-term injury. Of course that's very bitter."

The hosts also lost Dan-Axel Zagadou before half-time, the defender trudging off with a thigh problem, making him doubtful for Thursday's Europa League knockout round play-off second leg against Rangers, in which Dortmund will attempt to claw back a 4-2 deficit.

Rose added: "The injuries are already clouding the victory."