Leverkusen's 5-0 win over Werder Bremen on Sunday secured Leverkusen's longed-for maiden German crown, with the victory breaking Bayern Munich's 11-year grip on the trophy and ridding the new champions of the unwanted 'Neverkusen' tag.

Immediately after his side's 43rd straight match without defeat, Leverkusen boss Xabi Alonso challenged Leverkusen to complete a trophy treble with a German Cup final against second-division Kaiserslautern already booked for May 25.

But first up is a meeting with West Ham at the London Stadium, where Leverkusen will kick-off with a 2-0 lead from the first leg in Germany.

"Rightly so, why would you not celebrate?" Moyes told reporters on Wednesday.

"To be the champions, you should celebrate, you should enjoy it because the moments go very quickly.

"I hope they've been downing (drinking) those big giant glasses of beer they get in Germany!," the Scot added.

West Ham will require something special to overturn a 2-0 deficit, but goalkeeper Lukasz Fabianski, who celebrates his 39th birthday on Thursday, said the Hammers know what it takes to mount a comeback from a seemingly impossible position.

Fabianski, a member of the Hammers team who were 3-0 down at Tottenham with 10 minutes to go in 2020 only to draw 3-3, said: "I think the confidence that we can take is from the experiences in recent years, games where we have been down and come back.

"The Spurs game is one of the best examples, being 3-0 down and to score three in 10-15 minutes.

"We've experienced some great moments as a team in recent history and that will help us prepare mentally for (Thursday's) game," the former Poland international added.

Meanwhile West Ham's Jarrod Bowen, who missed the first leg, and Sunday's Premier League loss at home to Fulham, could return following a hip injury after the Hammers' 19-goal top-scorer this season took part in training on Wednesday.

"It was great to see Jarrod out there," said Moyes.

"We're not sure yet. I would never risk a player if I thought they were injured but you always want your best players back in, your goalscorers as well, and Jarrod has been that this season."