It's the first time since 2016 that Borussia Dortmund have beaten Bayern Munich in the Bundesliga.
The ex midfielder, who spent four seasons as one of the Schwarzgelben praised his former team's match strategy against their biggest rivals in the Bundesliga.
Both Dortmund and Bayern started the match with well balanced line-ups.
It was 1-0 at the break, but Dortmund drew level when Manuel Neuer brought Reus down in the area in the 49th minute and the skipper calmly converted the penalty. "Dortmund have very quick players and we should have been more compact".
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They claim that the criticism they have faced is an "organised and clear" attempt to damage their reputation. I believe in this team". " They're the games that I love to be involved in ".
Reus got parity again for the hosts in the 69th minute with an incredible half-volley in the centre of the box following a brilliant cross by Lukasz Piszczek, 2-2. Yet the joy of the home crowd was short-lived when Lewandowski again headed in at the far post after a quick combination for his 12th goal in nine games against his former club.
After a pulsating clash, however, it was Dortmund who came out on top.
Bayern had a chance for a late equaliser, which nearly arrived from a free-kick from Kimmich but it was mistakenly headed back towards his own goal by Reus, who could only watch as the ball dropped past the post.
Nelson, on loan from Arsenal, settled the matter with his sixth goal in seven league games just two minutes after coming on.
Earlier, Gladbach tightened their hold on second place with as 3-1 victory at Werder Bremen courtesy of a hat-trick from forward Alassane Plea, who also took his season's tally to eight goals.