Leverkusen scored late to continue their unbeaten run this season and advance to the Europa League semi-finals with a 1-1 draw at West Ham on Thursday, while Liverpool were eliminated by Atalanta.

Klopp's side won 1-0 on the night thanks to Mohammed Salah's early penalty, but paid the price for a 3-0 defeat at home in the first leg.

"We won the game and that was the reaction we wanted to show ... but Atalanta deserve to go through, 100 per cent. It is mixed emotions," Klopp said.

Liverpool beat Chelsea to lift the Carabao Cup in February and remain a chance to win the Premier League, despite handing the initiative to Manchester City with last weekend's surprise home loss to Crystal Palace.

Leverkusen, who have already clinched the Bundesliga title and are in the semi-finals of the German Cup, are the first team from the top five European leagues to go unbeaten in 44 matches - moving one ahead of Juventus.

The German side sealed their spot in the semis after Jeremie Frimpong's 89th-minute equaliser cancelled out Michail Antonio's opener for West Ham. Leverkusen had defeated West Ham 2-0 in the first leg.

They will now have a rematch of their 2023 semi-final against Roma, who defeated AC Milan 2-1 (3-1 on aggregate). Last year, the Italians advanced to the final but lost to Sevilla.

"We're happy to have reached the semi-finals, that's not an everyday thing," Leverkusen midfielder Granit Xhaka said.

"We have to be proud of what we've achieved today."

Atalanta will face Marseille, who defeated Benfica 4-2 on penalties.

Roma had the 1-0 lead from the first leg and early goals from Gianluca Mancini and Paulo Dybala put the them firmly in control.

Roma were down to 10 men from the 31st minute when Zeki Celik was shown a red card for a foul on Rafael Leao, but Milan failed to make the best out of it and only got a late consolation from Matteo Gabbia.

In the Europa Conference, Fiorentina needed extra-time to overcome Victoria Plzen 2-0 and reach the semi-finals, while Aston Villa also advanced after defeating Lille 4-3 on penalties.

Villa, who had the 2-1 advantage from the first leg, scored in the 87th minute to force extra-time and eventually penalties as they reached their first continental semi-final since winning the European Cup in 1982.

World Cup-winning goalkeeper Emiliano Martinez said it was his destiny to be the penalty shoot-out hero.

"It has been a hell of a ride all of my career. I am a believer and a hard worker and it was my destiny today," the Villa keeper said on TNT Sports.

Villa will face Olympiacos after they won 3-2 on penalties against Fenerbahce, while Fiorentina will take on Club Brugge, who defeated PAOK 2-0.

Australian Associated Press