Rafael Benitez has challenged record signing Miguel Almiron to fulfil his potential in the Premier League after completing his move to Newcastle.

Almiron, who could make his debut at Tottenham on Saturday, is now the Magpies’ most expensive acquisition after owner Mike Ashley finally sanctioned a purchase costing in excess of the £16million then chairman Freddy Shepherd paid to lure Michael Owen to Tyneside from Real Madrid in 2005.

Press Association Sport understands Ashley, who has come under refreshed fire from disgruntled supporters in recent weeks, played a prominent role in pushing through the deal, which was brokered by managing director Lee Charnley and head of recruitment Steve Nickson.

Almiron, who began his career with Cerro Poteno in his native Paraguay before heading for the United States via Argentinian side Atletico Lanus, was twice named in the MLS Best XI during his time in America.

Almiron’s arrival was confirmed hours after that of full-back Antonio Barreca, who has joined the club on loan from Monaco until the end of the season with an option to make the move permanent.

Whether the deadline day activity will be enough to persuade Benitez to extend his stay at St James’ Park – he is out of contract at the end of the season – remains to be seen, with the 58-year-old Spaniard seeking assurances over the club’s ambition.