Flick said it was one of those comebacks that nobody forgets easily, adding it was not easy to win after Borja Iglesias netted a hat-trick to give Celta a 3-1 lead.
Barcelona will be aiming to open up a seven-point lead at the top of LaLiga table when they welcome Europe-chasing Celta Vigo on Saturday.
Barcelona coach Hansi Flick on Friday demanded to meet with La Liga officials over what he called a "joke" schedule, saying Spanish football was failing to take care of players.
"They made our lives very hard but what was important is we made it to the semi-finals."
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.
Barcelona extended their advantage in the Spanish top flight with a 1-0 win at Leganes on Saturday, completing a 12-match unbeaten run and moving seven points clear of second-placed Real Madrid.
Rivals Real Madrid and Barcelona, locked in a title battle in La Liga and set to face off in the Copa del Rey final, have "a lot of respect" for each other, says Los Blancos coach Carlo Ancelotti.
Spain's National Sports Council (CSD) on Thursday upheld an appeal filed by Barcelona players Dani Olmo and Pau Victor which will allow them to play for the club until the end of the season, a decision LaLiga said they would appeal.
But Robert Lewandowski came to the rescue at 1-1 as the 36-year-old netted twice to guide Barcelona to the win. The Polish striker also extended his tally at the top of LaLiga's scoring chart to 25 goals.
Flick said it was one of those comebacks that nobody forgets easily, adding it was not easy to win after Borja Iglesias netted a hat-trick to give Celta a 3-1 lead.
Barcelona will be aiming to open up a seven-point lead at the top of LaLiga table when they welcome Europe-chasing Celta Vigo on Saturday.
Barcelona coach Hansi Flick on Friday demanded to meet with La Liga officials over what he called a "joke" schedule, saying Spanish football was failing to take care of players.
"They made our lives very hard but what was important is we made it to the semi-finals."
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.
Barcelona extended their advantage in the Spanish top flight with a 1-0 win at Leganes on Saturday, completing a 12-match unbeaten run and moving seven points clear of second-placed Real Madrid.
Rivals Real Madrid and Barcelona, locked in a title battle in La Liga and set to face off in the Copa del Rey final, have "a lot of respect" for each other, says Los Blancos coach Carlo Ancelotti.
Spain's National Sports Council (CSD) on Thursday upheld an appeal filed by Barcelona players Dani Olmo and Pau Victor which will allow them to play for the club until the end of the season, a decision LaLiga said they would appeal.
But Robert Lewandowski came to the rescue at 1-1 as the 36-year-old netted twice to guide Barcelona to the win. The Polish striker also extended his tally at the top of LaLiga's scoring chart to 25 goals.
Leading LaLiga with 63 points, Barca face Girona on Sunday after only two days rest following their 3-0 triumph over Osasuna and over the next 17 days they have six matches in all competitions.
