Barca top the LaLiga standings ahead of Real Madrid with eight matches left and will play their arch-rivals in this month s Copa del Rey final.

"We can dream, but players and coaches must keep our feet on the ground," Flick told reporters on Tuesday.

"We have to look at what we have achieved, based on hard work, and it must not be the end. We have to pull out all the stops to keep going.

"We want to continue without losing this year, but we have to perform at our best against a very strong rival."

Dortmund finished runners-up to record 15-times European champions Real in the Champions League last season, but have struggled domestically in this campaign and are only eighth in the Bundesliga.

They suffered another blow this week when German centre back Nico Schlotterbeck was ruled out for the rest of the season due to a serious knee injury.

"I prefer to play against the better team. I m sorry about Nico s loss and I wish him well. Dortmund have a lot of classy players and they are in the quarters for a reason. The absentees will have little influence on them," Flick said.

The former Bayern Munich coach was asked about Brazilian forward Raphinha, who was only a substitute in Barca s 1-1 LaLiga home draw with Real Betis on Saturday.

Raphinha, 28, has scored 27 goals and provided 20 assists in 44 appearances in all competitions for Barca this season.

"We have tried, after the international break, to get him back on his feet. What I see in the session is the same as I saw before: he s very active, awake, dynamic... it shows that he s ready for tomorrow s game," the German said.