The Schwarzgelben won 3-2 on Saturday thanks to a Marco Reus hat-trick, after going 2-0 behind, to set up their tie with Real Madrid in midweek
Marking his 300th Bundesliga game as a coach, the Schwarzgelben boss had little cause to celebrate the occasion in the opening 20 minutes as his side fell 2-0 behind.
But he was rescued by a Marco Reus hat-trick, with the second goal coming from the spot after Georg Niedermeier's dismissal for the hosts, and Klopp felt that Dortmund were good value for the win despite the poor start.
"It was the worst possible start for us," he told the club's official website.
"Perhaps we needed those two goals to respond. In the second half we were great and kept going. We have exploited the red card and deserved to win.
"We definitely needed the result. Now we need to continue. We have games that are never that far away from each other and didn't want to lose and have a bad feeling in the Champions League.
"In Madrid there will be major problems we have to deal with, as they always cause problems for anyone that goes there. Real is a big favourite.
"First of all though, the guys have to recover as they are very tired after this intense game in Stuttgart."
The result moves Dortmund back up to second after Schalke had displaced them with Friday's 2-0 win over Hertha Berlin.