ROTTERDAM, Netherlands - Germany’s "Invincibles" Bayer Leverkusen opened their Champions League campaign with a resounding 4-0 away win over Feyenoord on Thursday, after running riot in the first half.

Florian Wirtz scored two, while Alejandro Grimaldo also got on the scoresheet and there was an own goal as Leverkusen were 4-0 up at halftime with the home side jeered off the pitch by their own supporters.

It proved a sobering start to their Champions League campaign for Feyenoord, Dutch league runners-up last season but struggling to find form since the departure of coach Arne Slot for Liverpool.

Leverkusen thoroughly outplayed them in the first 45 minutes and then competently dealt with an attempted home comeback after the break.

Leverkusen, who became the first team to finish a Bundesliga season unbeaten as they romped to the title last campaign, were ahead in the opening five minutes as Wirtz took advantage of a defensive slip by Ramiz Zerrouki to open their account.

Strong running

Dutch international Jeremie Frimpong then set up the next two goals with his strong running down the right flank, carving up the home defense.

The first was for Grimaldo in the 30th minute with some help from a clever no-look pass by Victor Boniface and the next a precision cross to the back post to find Wirtz flying in to convert unchallenged in the 36th minute.

ALSO READ: Last-gasp Wirtz goal earns Leverkusen 3-2 win at Gladbach in Bundesliga opener

Just when it seemed it could not get worse for the Dutch side, Leverkusen went four up on the stroke of halftime.

A freekick found centre back Edmond Tapsoba at the back post as his header back into the danger zone struck Feyenoord keeper Timon Wellenreuther on the foot and it ricocheted slowly backwards over the line for an own goal.

Feyenoord captain Quinten Timber had a good chance to pull one back 10 minutes into the second half but was denied by a strong save from Leverkusen goalkeeper Lukas Hradecky.

"The way we lost is just sour. I don't think we played badly at all. But we gave away those goals far too easily," Timber told reporters.

While the home side showed more spirit and energy in the second half, they rarely threatened to score, although a 74th minute effort from substitute Ayase Ueda was ruled out for offside.

Leverkusen were close to a fifth goal as the match went into stoppage time, with David Hancko clearing off the line from Aleix Garcia.

READ MORE: Leverkusen have no time to soak in 'Neverlusen' season

The Germans are home to AC Milan in their next Champions League encounter on Oct. 1 while Feyenoord play in Spain at Girona the next day.