Terzic lauds Dortmund's defensive resilience after record-equalling win puts them top
Dortmund headed into Friday's game second to Bayern Munich only on goal difference after an imperious run of form since the return of domestic football following the Qatar World Cup.
Meanwhile, Leipzig, led by former Dortmund boss Marco Rose, were four points off top spot themselves and looking to move within striking distance of the top two.
After Julian Brandt had seen a goal ruled out for offside for the hosts, captain Marco Reus scored from the spot after being felled by Leipzig goalkeeper Janis Blaswich to put Dortmund ahead and move into second on the club's all-time goalscoring list.
Emre Can then saw a shot from the edge of the box somehow find its way in to give his team a commanding 2-0 lead at the break.
Leipzig improved after the break though and halved the deficit when Emil Forsberg slid in to turn David Raum's cross into the net, setting up a grandstand finish.
Rose's men piled on the pressure, and an incredible goal-saving block was needed from Nico Schlotterbeck to deny Timo Werner's powerful goal-bound effort in the dying seconds as Dortmund saw the game out for three points to move top, with Bayern not playing until Saturday when they face Stuttgart.
Terzic was delighted after watching his team's last-ditch defending pay off, telling DAZN: "That was an absolutely top game, we're very happy.
"We played very well in the first half, in the second half we defended passionately. We saved it over the line, it wasn't easy to score a goal against us today."
Reus was relieved to pick up a 10th straight win in all competitions despite Dortmund's low-key second-half display, saying: "In the second half we didn't manage to keep the ball, to get more solutions, that wasn't so good anymore.
"But we're very happy to have won the 10th competitive game in a row. In the end, I'd rather win than play well and lose. It's all about hard work, we've shown that in the past few weeks and today."
Rose was frustrated by the loss after a much-improved performance in the second half, explaining: "The result is difficult to accept, the second half clearly went to us.
"Dortmund were very efficient. It was a decent game from us at the back, I didn't feel like we were clearly inferior. Over 90 minutes, it's hard to accept losing a game like that."