Dortmund's two-goal hero Kevin Grosskreutz celebrates after scoring his team's opener against Bayer Leverkusen.
STORY HIGHLIGHTS
- Kevin Grosskreutz scores twice as Borussia Dortmund extend Bundesliga lead
- He also sets up third goal for Mario Gotze in 3-1 win at Bayer Leverkusen
- Leverkusen fall 13 points behind and drop to third place on goal difference
- Dortmund, seeking first German league title since 2002, have 15 wins from 18 matches
(CNN) -- Borussia Dortmund delivered a devastating blow to Bayer Leverkusen's title hopes with a 3-1 away victory that extended the German league leaders' advantage to 13 points.
Leverkusen went into the match in second place on goal difference ahead of Mainz, but paid the price for poor second-half defending as Dortmund made the perfect start following the Bundesliga's mid-winter break.
Two goals from Kevin Grosskreutz and another from teenager Mario Gotze gave Jurgen Klopp's team a ninth victory in 10 away trips and 15 from 18 matches overall, in front of a stunned sellout crowd of 30,210 at the BayArena.
"I have been going to watch Dortmund since 1994 and I know what it's like to win the league title as a fan on the terraces," Grosskreutz said of his team's hopes of a first championship since 2002.
I have been going to watch Dortmund since 1994 and I know what it's like to win the league title as a fan on the terraces
--Kevin Grosskreutz
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"I have been dreaming of this since I was a little boy, and I'd love to hold the cup in my hands."
Dortmund hit the post early in the first half with a header by Sven Bender, but Leverkusen slowly got into the game despite leaving veteran Germany international Michael Ballack on the substitutes' bench.
However, Grosskreutz broke the deadlock four minutes after the break when Leverkusen defender Manuel Friedrich failed to deal with a long throw by Lukasz Piszczek and actually diverted the ball into the midfielder's path with his arm.
Grosskreutz then made it 2-0 in the 53rd minute after Poland striker Robert Lewandowski headed on a long clearance as the home defense was again caught out.
The 18-year-old Gotze, who made his international debut for Germany last year, then effectively ended the match two minutes later as he calmly slotted the ball through the legs of Leverkusen keeper Rene Adler for his fifth goal this season after being set free by Grosskreutz.
It was Gotze's last significant contribution as he was replaced by top scorer Lucas Barrios, who forced a fine save from Adler in the 70th minute.
Stefan Kiessling finally pulled one back for Leverkusen with 10 minutes to play as he bravely poked in a cross by Renato Augusto before colliding with the goal-post.
The striker had another chance soon after, but shot wide as Leverkusen dropped down to third place.
In Saturday's fixtures, Mainz travel to Stuttgart while fifth-placed defending champions Bayern Munich will try to reduce a 17-point deficit on Dortmund with victory at Wolfsburg.
