The Napoli defender is sure his team can bounce back from the disappointing result against the Serie A holders on Saturday
Juve took a 3-0 lead thanks to goals from Danilo, Gonzalo Higuain and Cristiano Ronaldo, but the visitors fought back, with Kostas Manolas, Hirving Lozano and Giovanni Di Lorenzo finding the net to pull level with the reigning Serie A champions.
With just 90 seconds left, however, Koulibaly tried to clear a cross from a free-kick and ended up knocking it past Alex Meret to hand the hosts three points.
And the centre-back spoke of his disappointment after the game, but he remains confident his side can bounce back.
“It’s an own goal that hurts me because it came after an incredible comeback,” the 28-year-old said on Twitter.
“I’m sorry but I have to, we have to accept it: we are strong. We have shown that. We’re going to prove it.”
Coach Carlo Ancelotti was not happy with his side’s display, despite their incredible turnaround in the second half.
“It was not a positive performance. The first hour we didn’t do well. But despite the 3-0 we stayed in the game, we came back,” he said.
“But my judgment would not have changed even with a 3-3 draw.
“Juventus played more on the counterattack at 2-0 and we had more control over the game, we gave Juve the chance to press and take confidence.
“We made so many mistakes, allowing them to press, to create problems, to show courage.
“Blaise Matuidi, for example, did an extraordinary job, but left room for Fabian Ruiz who remained isolated. We never managed to get to him with a clean pass. Too bad, the spaces were there.”
He added: “Juventus have so much character and quality, we know that they always step up in the important moments of the season.
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“We wasted an opportunity today.