Jerome Boateng says Bayern Munich must improve for Wednesday's Champions League semi-final, first-leg, at Barcelona or not bother travelling to Spain following their "careless" German Cup exit.

Bayern's dreams of repeating their 2013 treble of European, league and cup titles this season were ended when they were knocked out of the German Cup semi-finals on Tuesday by Borussia Dortmund on penalties.

The defeat came just two days after winning the Bundesliga title.

Having taken a first-half lead through Robert Lewandowski, Bayern dominated until the 70th minute when Dortmund brought on attacking midfielder Henrikh Mkhitaryan.

The visitors created a string of chances leading to Pierre-Emerick Aubameyang's late equaliser which took the game to extra-time and Bayern failed to convert any of their four spot-kicks in the shoot-out.

Boateng said they can ill afford anything less than a top performance at the Camp Nou against the Spanish league leaders, with the return leg on May 12.

"Barcelona are one of the best teams in the world and we'll need a top performance," Boateng told football magazine Kicker.

"If we play like we did after the 70th minute against Dortmund, then there is no need for us to even go to Barcelona.

"Dortmund came back into the game and we gifted them the chance to play in the final.

"How many chances did they have up until 1-1? None.

"We are too careless. We have to defend and attack again as a team. We make too many mistakes when we take the lead.

"We give the ball away too quickly, play too many long balls and are too lax.

"We had a big chance against Dortmund and I am bitter about how things worked out as it didn't have to be that way."

The loss to Dortmund was only Bayern's fifth defeat in 45 games this season.