Man Utd rivals Athletic Club confirm injury nightmare before Europa League semi-final

have confirmed that Nico Williams has suffered an ill-timed groin injury, ruling him out of Sunday's clash against . The Spanish outfit's star winger now faces fitness uncertainty ahead of the semi-final tie with Manchester United, which kicks off with the first leg on May 1.

Williams has less than two weeks to return to contention before United visit the Estadio de San Mames, leaving Ernesto Valverde sweating. He has played a crucial role in Athletic's run to the final four, registering five goals and two assists in 12 games throughout the campaign. But the 22-year-old's return date is up in the air, with Las Palmas also to play before hosting their mammoth European tie comes around.

On Saturday, a club statement : "Nico Williams will not travel to Madrid for the match against Real Madrid at the Santiago Bernabeu Stadium due to groin pain. The outcome is pending."

Williams is among the most dangerous players in Valverde's arsenal, joining brother Inaki Williams and Oihan Sancet in an ultra-talented attacking trio behind the striker.

The Williams brothers have scored five goals apiece in the Europa League this season and boast the quality to put United to the sword.

But if his injury extends into the crunch semi-final tie, Athletic will be without a crucial cog in Valverde's resolute team.

United face a daunting task against the Spaniards, who finished one place higher than them in second in the league phase.

Athletic have the added motivation of playing in their home stadium should they reach the final to face Tottenham Hotspur or Bodo/Glimt.

They haven't tasted defeat at the Estadio de San Mames since January 16, losing just three times across the 18 matches that followed.

United have reason to be optimistic, though, after conjuring up a miraculous comeback in the final six minutes of extra-time against Lyon.

The Red Devils trailed 4-2, having led 2-0, in the 114th minute before Bruno Fernandes, Kobbie Mainoo, and Harry Maguire erupted the roof off Old Trafford.

Ruben Amorim's side haven't lost once in their 12 Europa League games this season and are the only remaining unbeaten outfit in European competition.

It has been a contrast from their Premier League campaign, which has left glory in Bilbao their only pathway to Champions League football next term.

Regardless of Williams' public status, Amorim will undoubtedly be preparing his players for the test of silencing the Spaniard in May.