The ex-Manchester City midfielder, who was sent off in last weekend's 2-1 Barclays Premier League win at Crystal Palace, missed last week's first-leg with a virus that saw him sent home from training last Wednesday.
But the Reds' vice-captain has now fully recovered and is fighting to feature for Jürgen Klopp's charges as they travel down East Lancs Road in their attempt to reach the quarter-finals of the competition.
The 30-year-old has been back in training all week and will be hoping to displace one of the starting eleven that helped establish the comfortable lead which they take to Old Trafford.
The manner of the first-leg victory, which saw Adam Lallana, Philippe Coutinho and Roberto Firmino all star - whilst Emre Can also excelled in central midfield - means Milner may be forced to settle for a place on the bench.
Reds skipper Jordan Henderson's place in the team could be under threat after a poor run of form, although he's unlikely to be dropped for such an important tie against Louis van Gaal's men.
Reds hoping to reach quarter finals of Europa League
Liverpool haven't reached the final eight of any continental tournament since reaching the semi-finals of the Europa League in 2009-10 under Rafael Benitez, before they lost out to Atletico Madrid on away goals.
But they stand a good chance of doing so this season thanks to goals from Daniel Sturridge and Roberto Firmino giving them a 2-0 advantage which means they only need to avoid a defeat by two goals or more to progress.
And the incentive of qualification for next year's Champions League for the winners of the competition adds extra importance to it, with a top-four finish in the league heavily reliant on the form of other teams.
Elsewhere, Liverpool's two postponed league matches - home games against Chelsea and Everton have finally been rescheduled after the two teams locked horns in the FA Cup sixth round last weekend.
Klopp and co. now host their bitter rivals just days before Everton's Wembley semi-final against either Manchester United or West Ham United on Wednesday 20th April, either side of a trip to Bournemouth and a home game against Newcastle United.
The final home game of the season was originally scheduled to see Liverpool face Watford on May 7th, but now instead - they will take on Chelsea in a midweek game on Wednesday 11th May under the Anfield floodlights.