ITV confirmed the speed merchant has put pen to paper on a new five-and-a-half year deal with Athletic Club, inserting a huge release clause of £38 million after the forward had been available for £15.3 million.
The signing of the contract was shared by the club on social media:
The new valuation is likely to scare off Premier League suitors in the near future, but Williams is a burgeoning talent in the Spanish game and will remain on the radar.
Kieran Gill of MailOnline added Liverpool were "seriously considering" making a quick-fire move for the youngster, who is recorded as the fastest player in La Liga. Arsenal boss Arsene Wenger is described as a "fan" of the 21-year-old, who is experiencing a breakout campaign with Bilbao in 2015-16.
According to OptaJose, Williams is the youngest player in Europe to reach double figures this season, netting 10 in all competitions:
10 - Iñaki Williams is the youngest player to score 10 goals in Europe this season. Feline. pic.twitter.com/0JvqkSaZ2r— OptaJose (@OptaJose) January 13, 2016
The Daily Mail's Sami Mokbel recently reported Liverpool manager Jurgen Klopp "isn't convinced" by £32 million signing Christian Benteke, who was purchased by former manager Brendan Rodgers, forcing the German to review his attack.
However, Aarons said Bilbao were trying to sign Williams to a new deal, complete with a €100 million (£76.3 million) release clause. It now appears they have tied the player to the club—gazumping Klopp's intentions.
Here is a video showing why Williams is desired by Liverpool and Arsenal:
The Anfield boss could quickly turn his attentions to recent target Alexandre Pato and form a late attempt to hijack Chelsea's move for the versatile striker.
Charlie Phillippe of the Express said the Premier League champions have agreed a three-year deal with the Brazil ace, but Klopp is not out of the race yet.
Pato's agent, Gilmar Veloz, told Brazilian media outlet UOL Esporte (h/t Phillippe) four clubs still have a chance of landing the former AC Milan star, including the Reds, with no firm bid on the table.
"The January market is very limited," Veloz said. "Chelsea, Liverpool, Sporting [Lisbon] and Benfica. All four have a chance. The guys [Kia Joorabchian and Giuliano Bertolucciare] are working on getting an offer, but nothing Corinthians are yet to receive one."
Klopp's attacking instinct and raiding style make Benteke an undesirable forward for his tactics, and Williams would have been perfect for a switch to Anfield.
Should Liverpool trigger Williams' new release clause?
The Spaniard is hungry and young, and he possesses the natural pace that will make him one of Europe's top attackers in the years ahead, if his current development continues.
Pato's history in Europe is blighted by his failure at Milan, and San Siro fans expected so much more from their prodigious forward.
However, at 26, there is time for the Brazilian to resurrect his career and ambitions in the world of English football. The history and future of Liverpool—with Klopp at the helm—could give them an advantage over a Chelsea team in decline when Pato signs a new deal.