Borussia Dortmund manager Thomas Tuchel said he was "shocked at how easy it was" for Odd to score in Thursday's Europa League tie, despite his side's thrilling 4-3 comeback.
Dortmund were put on the back foot immediately when their Norwiegan opponents scored just 13 seconds into the game. Rafik Zehninija turned defender Gonzalo Castro and sent a cross which Jone Samuelsen headed home.
Tuchel said his players were not mentally ready to play when the game began.
"We really didn't want that," he said. "We weren't prepared for what happened at the start, and weren't physically or mentally there yet.
"I was shocked at how easy it was for them to score against us. We let them put in easy crosses.
"We stepped it up after the first goal, hitting the crossbar, before the opposition's second attack made it 2-0."
After Espen Ruud's free kick made it 3-0, Dortmund were able to rally when Shinji Kagawa, Pierre-Emerick Aubameyang, and Henrik Mkhitaryan scored in the second half, and Tuchel praised his players' resiliency and desire to win.
"We showed good morale and turned it around, which was impressive. In the end we deserved to win, although we could have done so more convincingly," Tuchel said.
"We can handle and shake off difficult situations. It's not just the fact that we came back from 3-0. The team showed great team morale, which bodes well for the future. The team showed a really positive development."
Dortmund needed all four of their goals to win, but Tuchel said his side could have scored many more.
"We could only be sure that it was actually a goal when the ball crossed the line. We had so many great chances," Tuchel said. "Unbelievable, even crossbar shots.
"We definitely could have won more convincingly, but we'd have had to defend much better at the beginning."
Dortmund will return to Germany for their home leg with a one-goal advantage, and Tuchel expects the next contest with Odd to go more smoothly.
"Before the game I said that a win is a good result -- in that sense I'm happy," he said. "With all due respect we're very confident that we'll be able to get a win at the second leg."