Manchester United will not only be focused on keeping fit ahead of their Europa League semi-final tie against Athletic Club starting in nine days' time, but also the state of their opposition. "It’s not the best moment or the best season to put some kids to play because they need a strong base to really show what they can do, but in this moment we need to do it," boss Ruben Amorim admitted after securing passage to the Europa League 's last-four. He made good of that promise during Sunday's defeat to Wolves by benching captain Bruno Fernandes, Casemiro, Diogo Dalot and Harry Maguire. As they are 14th in the Premier League , Man United are truly putting emphasis on European glory and the bonus prize of qualification for next season's Champions League . Then there are their opponents, Athletic, who are in La Liga's top-five battle for the Champions League and remain in the hunt for continental silverware. But this is proving to be a challenge for manager Ernesto Valverde, who has some recent injuries to contend with. MEN Sport looks into Athletic's issues with exciting slowly building for the semi-finals. Of biggest concern for Athletic is the absence of Nico Williams. The 22-year-old is one of Europe's brightest talents and is his club's second-top goalscorer and joint-second-top assister this term. He went off with discomfort after scoring in the quarter final second-leg victory that sent his side through at the expense of Rangers. It was later revealed in a club statement to be a groin problem . With that, they promised the full extent of the injury will be revealed soon - though not before he missed Sunday night's La Liga defeat to Real Madrid. Williams' absence was clearly felt as they ended up sitting in, mustering only one attempt on target, before conceding in the third minute of injury time. Speaking about Williams in his press conference following defeat to Real Madrid, Valverde said: "It's something he's been carrying for a short time and it didn't come on suddenly. "We hope to recover for these upcoming matches. It's true that the season is long and we have to get to the end. "We're in the final stretch and it shows because we always have to be at 100%, but physically, my team is a guarantee." Left-back Yuri Berchiche is another player Athletic have had to take caution with lately. On April 9, he lasted 34 minutes in a La Liga clash with Villarreal before succumbing to a 'moderate' calf injury. He would go on to miss both legs against Rangers and the fixture that fell in between against Rayo Vallecano. Valverde opted to keep the 35-year-old on the bench for the entirety of the match against Real Madrid and another decision will be required for Wednesday's match against Las Palmas, which is directly before Man United's visit. Yeray Alvarez, a central defender, has suffered persistent fitness issues throughout 2025 so far. Attempts are being made to manage this ahead of the Europa League semi-finals. Most recently preventing him from playing against Villarreal earlier this month was an adductor issue, though the 30-year-old returned to play both full legs of the quarter final against Rangers. In the middle he remained benched vs Rayo and the same happened on Easter Sunday at the Santiago Bernabeu.