Guinea international Guirassy became the competition's outright top scorer with his 10th goal after an hour before turning provider with a fine cross for Pascal Gross to net the second for last season's runners-up.

Karim Adeyemi struck the third as Dortmund's rapid counter-attack sliced open the hosts at the Jose Alvalade Stadium to complete their first leg victory.

Sporting controlled the first half but Dortmund stepped up several gears in the second to claim their first win under new coach Niko Kovac, in his second match at the helm.

"The lads did a great job," said Kovac, praising his team's "mentality, physicality and aggression".

Dortmund kept their first clean sheet in 14 matches across all competitions as they showed flashes of the quality which saw them stun Europe's giants last season.

"That (win) was important," Gross told Amazon Prime.

"You could tell in the first half that we weren't brimming with confidence, but after the break, we played a very decent game."

Sporting, who finished 23rd in the group phase and only just avoided the cut, played with confidence in the first half and made the early advances.

Rui Borges, appointed in December to replace Ruben Amorim's struggling successor Joao Pereira, has steadied the ship quickly in Lisbon.

Former Barcelona forward Francisco Trincao's effort from range was caught by Dortmund goalkeeper Gregor Kobel and Maxi Araujo's vicious strike cracked against the crossbar with the stopper beaten.

Kobel used his forearm to keep out a rocket from Conrad Harder, starting up front in place of top scorer Viktor Gyokeres, on the bench after a thigh injury.

Former Bayern Munich coach Kovac's Dortmund threatened for the first time late in the half when winger Jamie Gittens cut in from the left with menace and pinged an effort narrowly wide.

'Fight until the end' 

Dortmund, who only just missed out on a top eight finish and automatic progress to the last 16, came out with far more intent in the second half and claimed their reward.

Rui Silva made a fine save to palm away Adeyemi's snap-shot and Gittens had a shot blocked after surging into the area.

Sporting responded by sending on Gyokeres for Harder, aiming to turn the momentum back in their favour.

However Dortmund took the lead moments later, with Guirassy netting with a superb looping header over Silva, from Julian Brandt's cross.

Nico Schlotterbeck bravely slid in to keep Gyokeres at bay before former Brighton midfielder Gross grabbed Dortmund's second.

Guirassy produced a superb whipped ball into the danger area from the right and Gross used his leg to improvise a finish from a few yards out.

With Sporting keen to find a foothold, Dortmund sprung forward on the counter to net their third.

Adeyemi fed Brandt and darted into the box, tapping home when the midfielder put the ball on a plate for him.

"After the (first) goal our spirits dropped and we felt it physically... the result ended up being unfair," said Sporting coach Borges.

"In the Champions League we need to be at 200 percent and we're not even at 100 percent."

The defeat leaves Sporting facing an uphill challenge in the second leg in Dortmund on February 19.

"In Dortmund, we will go with the mentality of trying to win, we know it will be difficult, but we are Sporting and we will fight until the end," said defender Matheus Reis.