The England international has travelled to Italy even though he has not featured since picking up a problem shortly after coming on as a substitute against Crystal Palace in March.
Lallana travelled to South Africa for treatment last month and boss Jurgen Klopp said last week that “one or two games might be possible for him”, but that there was “no chance” he would feature against Roma on Wednesday.
Liverpool are currently short of midfield options as both Alex Oxlade-Chamberlain (knee) and Emre Can (back) are sidelined.
Defender Joe Gomez has not flown to Rome with his club colleagues after picking up an ankle problem in Saturday’s 0-0 draw with Stoke.
Forward Sadio Mane, who was left out of the squad at the weekend, was on the plane, as were captain Jordan Henderson and defender Trent Alexander-Arnold, both of whom had minor fitness concerns following the Potters game.
Five-time European Cup winners Liverpool hold a 5-2 advantage from the first leg at Anfield and will be hoping to progress to their eighth final.
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