The Red Devils capitalised on a red card to Bilbao's Dani Vivian, with Casemiro and Bruno Fernandes (twice) scoring before the break to end the hosts' perfect home record in the competition.

The game turned in United's favour after a shaky start. Bilbao pressed early, with Alex Berenguer's shot saved and Inaki Williams heading just over.

However, United struck first in the 25th minute when Harry Maguire's pinpoint cross found Manuel Ugarte, who nodded it to Casemiro for a headed finish.

Moments later, Vivian's tug on Rasmus Hojlund earned a red card and a penalty, which Fernandes calmly dispatched. Fernandes struck again before half-time, slotting home after a slick move, while Noussair Mazraoui rattled the crossbar in stoppage time.

After the interval, United managed the game expertly, with Casemiro hitting the post and Julen Agirrezabala denying late efforts from Fernandes and Alejandro Garnacho.

Bilbao, frustrated and outmanned, failed to muster a response, suffering only their second defeat in 11 matches.

Manager Rúben Amorim praised his side's resilience but urged caution. "The result is great, but we struggled early," he said. "Casemiro's goal and the red card changed everything. We had chances for more, but this isn't over. Bilbao are intense and can hurt us at Old Trafford."

Reflecting on his squad, he added, "Players like Casemiro, Maguire, and Fernandes bring vital experience. Even Ugarte and (Patrick) Dorgu were nervous—it's a semi-final."

Amorim attributed United's stronger European form to fortune. "In the Premier League, we've conceded early and struggled," he said. "In Europe, we've had luck at key moments. We're underperforming domestically, but we want to give our fans something special."

Recent posts on X from United's official account hailed the "clinical" performance, while Fernandes shared, "Big step forward, but we stay focused for the second leg."

Bilbao's Ernesto Valverde, meanwhile, vowed a comeback, posting, "We'll fight until the end at Old Trafford."

With the final set for Bilbao's San Mamés, United are firmly in the driving seat, but Amorim's men know the job is only half done.

Man Utd crush Athletic Bilbao in Europa League semi-final