''We made elementary mistakes, tactical mistakes, especially in the beginning. We lacked concentration,'' Loew said. ''Overall in the first half, the whole defense was very erratic. The opponent had too much space. But you could see some players were missing match practice. The freshness wasn't there.''
Jose Ariel Nunez opened the scoring with Paraguay's first shot in the ninth minute, and more sloppy defending allowed Wilson Pittoni to make it 2-0 four minutes later.
Ilkay Gundogan pulled one back in the 18th, and Mats Hummels sprung the offside trap for Thomas Mueller to equalize in the 31st.
But Samudio restored Paraguay's lead before halftime, when former Bayern Munich striker Roque Santa Cruz found him unmarked at the far post.
Bender saved the home side's blushes in the 75th, when he beat Oscar Romero to the ball, took it on his chest and volleyed into the far corner.
''I'm not worried,'' said Germany captain Philipp Lahm. ''Next time we'll have time to work together, and we'll be better. It's normal when you have players coming together from different teams, all with different philosophies.''
It was a frustrating evening too for Miroslav Klose, back at the stadium where he started his professional career, as he failed to score the goal needed to equal Gerd Mueller's record of 68 for Germany despite several good chances.
But Paraguay captain Cruz was happy.
''We have a very young team. Not many of our players have experience abroad, so it's a very nice result,'' Cruz said.
The visitors were well-organized throughout - contrary to the German defense - managing to stifle space in midfield and quickly launching long passes to counterattack.
Pittoni's simple ball over the defense allowed Nunez in to rifle his shot past Manuel Neuer.
''We put no pressure on the player in midfield to stop the long ball,'' Loew said.
Sami Khedira botched his clearance after Neuer punched away Samudio's cross, and Pittoni volleyed the ball 20 meters into the left corner. It was Paraguay's second shot.
''Normally he has to clear the ball,'' Loew said.
Gundogan scored with a curling shot inside the left post, when Justo Villar got his hands to the ball but was unable to keep it out, and Germany deserved to equalize when Mueller stayed cool to pick his spot.
Samudio's goal left the home fans whistling as the teams left for the break.
Germany improved for the second half, though missed several chances before Bender finally equalized.
''Of course the performances will improve once the players get into their seasons with their clubs,'' Loew said. ''We will - like we always do - improve through September and October.''
Germany has World Cup qualifiers against Austria and the Faeroe Islands in September, and then against Ireland and Sweden in October.
''We can't play like that against Austria. It's a warning shot,'' said Neuer. ''We need to analyze it and learn from it.''
