Viktor Gyokeres transfer talk heats up as Ruben Amorim demands passion for Man Utd
Manchester United are intensifying their search for a new striker to address their goal-scoring woes, with Sporting CP's Viktor Gyokeres emerging as a prime target.
The tie carries extra weight, with the final of the competition also scheduled to take place at Bilbao's home ground later this month.
Bilbao have battled their way to this stage with impressive victories over AS Roma and Rangers, driven by a mix of youth and experience.
Williams, a standout performer this season, has recovered from a recent groin injury and is named in the 23-man squad.
Having featured in the club's pre-match infographic, the dynamic winger is tipped to start for the first time in two weeks.
The Basques will, however, be without top scorer Oihan Sancet, who picked up an injury in the 1-0 win over Las Palmas and is ruled out of the first leg. His absence is a blow to the hosts, who will look to others to provide attacking impetus.
Two veterans - Yuri Berchiche and Oscar De Marcos - also featured in the club's promotional materials, often a signal of inclusion in the matchday squad.
Berchiche, 35, returned to full action against Las Palmas and was influential against Roma in the last round. De Marcos, 36, has started all six of Bilbao's Europa League matches so far.