The Uruguayan, signed from Benfica for an initial fee of €75m ($73m, £66m) that could top €100m, was regularly sidelined by Jurgen Klopp in the early months of his career at Liverpool despite an early season concern for the Reds.
Liverpool have won just three of their opening nine games of the campaign and are already 11 points off the Premier League's pace and with work to do to reach the last 16 of the Champions League ahead of Rangers' visit to Anfield on Tuesday.
Nunez scored twice in his first two matches in Liverpool's victory over Manchester City in the Community Shield and drew 2-2 with Fulham over the opening weekend of the season.