Ten Hag was keen on signing Nunez from Benfica before the Uruguayan agreed a £64m switch to Anfield.
The 22-year-old was viewed as a long-term replacement for veteran striker Cristiano Ronaldo.
But with like-for-like replacements now hard to come by, ten Hag is changing his plans.
ESPN reports that the Dutchman now wants to sign a 'versatile' forward who can play across the front line.
The Red Devils are closing in on the signing of Frenkie De Jong, while Christian Eriksen may also join a free transfer.