Bayer Leverkusen cruised to a 4-0 win over Feyenoord upon their return to the Champions League, but head coach Xabi Alonso said the result did not come easy.

Florian Wirtz's brace along with Alex Grimaldo's strike and Timon Wellenreuther's own-goal handed Leverkusen a comfortable advantage at the break. 

The Bundesliga champions netted four goals in the first half of a game in a major European competition for just the third time after doing so twice in 1994 against PSV Eindhoven (4-2 HT) and GKS Katowice (4-0 HT). 

Alonso's side also became the first away team to lead by four goals at half-time of a Champions League game since Bayern Munich led 4-0 at Viktoria Plzen in 2022.

Despite the scoreline suggesting a comfortable outing for Leverkusen, Alonso credited his side's disciplined performance in a goalless second period. 

"We were not lucky, but efficient in the first minutes. We needed a bit more control on the build-up to find the free spaces," Alonso said. 

"We have good players who understand what the game requires. They are flexible.

"We need to have those registers... be flexible during the game."

Leverkusen's triumph saw them record their joint-biggest win in the Champions League (4-0 vs. Shakhtar Donetsk in October 2013). 

It was also their biggest victory away from home in any European competition since beating Celtic 4-0 in the 2021-22 Europa League.

Alonso's side return to Bundesliga action this weekend when they welcome Wolfsburg to the BayArena on Sunday.