Germany winger Marco Reus claimed a hat-trick on his comeback as Borussia Dortmund hammered Legia Warsaw 8-4 on Tuesday in a record Champions League result which yielded seven first-half goals.

The 12-goal haul in Dortmund bettered the record set in the Monaco-Deportivo game of 11 goals for a Champions League game.

With Dortmund already through to the last 16, the huge win keeps them top of Group F, two points clear of Real Madrid.

But despite the record rout, Dortmund coach Thomas Tuchel has some defensive problems to iron out.

"It was a great game for the spectators, but we shouldn't have leaked those four," said Dortmund goalkeeper Roman Weidenfeller, in for injured Roman Burki, who has a fractured hand.

"We have to defend better, this is the Champions League and you have to present yourself better than that."

Dortmund's Shinji Kagawa and Legia's Aleksandar Prijovic both finished with two goals each thanks to some poor defending by both teams.

Reus, who captained Dortmund, made his return after 185 days out with an adductor injury which ruled him out of June's European championships.

It was his first match since Dortmund lost the German Cup final to Bayern Munich on penalties in Berlin on May 21.

Tuchel made nine changes to his starting line up after admitting his side looked tired mentally and physically from Saturday's 1-0 win over Bayern Munich.

Only defenders Marc Bartra and Matthias Ginter kept their places in Dortmund's starting line-up.

The match got off to an explosive start.

Legia took an early lead when Prijovic was given too much space in the area to chip his shot home and stun the Dortmund crowd on 10 minutes.

But Borussia roared back with five goals in 16 minutes.

Their first three goals came in 198 seconds when Kagawa headed home on 17 minutes, then slotted a second just a minute later.

To compound Warsaw's problems a clearance punch from goalkeeper Radoslaw Cierzniak clattered off Nuri Sahin's chest and into the Legia goal to make it 3-1 on 20 minutes.

Prijovic pulled another goal back for Warsaw on 26 minutes, and could have claimed a hat-trick when his chip hit the crossbar moments later.

Dortmund's French winger Ousmane Dembele made it 4-2 when he beat several defenders to fire home on 29 minutes.

He then helped Kagawa set up Reus for his first on 32 minutes.

Dembele then weighed in with his third assist of the night with a superb cross to allow Reus to claim his second and Dortmund's sixth on 52 minutes.

Warsaw midfielder Michal Kucharczyk pulled a third goal back for Legia on 57 minutes before Pierre-Emerick Aubameyang came off the bench to hit the post for Dortmund.

Dortmund defender Felix Passlack then scored his first Champions League goal before Hungary striker Nemanja Nikolic netted Warsaw's fourth in the final ten minutes.

Reus wrapped up his hat-trick in the 93rd-minute when he converted Aubameyang's final pass at point-blank range.