Hansi Flick is determined to keep his Barcelona team grounded as they approach their Champions League quarter-final tie with Borussia Dortmund as heavy favourites.

Barca have not lost a game since the turn of the year and are still in the hunt for a possible quadruple this season.

The Blaugrana top LaLiga ahead of Real Madrid with eight matches left and will play their arch-rivals in this month's Copa del Rey final, having already beaten them to win the Supercopa de Espana in January.

They are also considered the Opta supercomputer's favourites to win the Champions League with a 23.1% chance, while they are given 78.2% chance of eliminating Dortmund ahead of Wednesday's first leg at home.

"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-time European champions Madrid in the Champions League last season, but they have struggled domestically this campaign and are only eighth in the Bundesliga.

They suffered another blow this week when Germany 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," Flick said. 

"Dortmund have a lot of classy players and they are in the quarters for a reason. The absentees will have little influence on them."

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

Raphinha, 28, has 27 goals and 20 assists in 44 appearances in all competitions this season, but he has struggled with fatigue since the recent international break.

"We have tried, after the international break, to get him back on his feet," Flick said. 

"What I saw 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."