Reguilon was an unused substitute for the FA Cup fourth-round win at Wycombe on Monday but has since suffered the problem and underwent a scan on Wednesday.
Although it is not serious, the injury comes at a bad time for Spurs, with Reguilon also expected to miss the Premier League game against Chelsea next Thursday, the FA Cup fifth-round at Everton on February 10 and the visit to Manchester City three days later.
Spurs’ other left-back Ben Davies is also a doubt to face the Reds after being forced off in stoppage-time in the 4-1 win at Adams Park with a knock, although the Wales international is hoping to be passed fit.
Japhet Tanganga has played at left-back under Jose Mourinho but not this season.
Reguilon hit the ground running after joining Spurs from Real Madrid in a double deal with Gareth Bale in September and provided excellent assists against Brentford and Fulham this month.
Mourinho has also said Dele Alli is injured and will not be involved against Liverpool, while Giovani Lo Celso remains sidelined with a hamstring problem.
Asked about the fitness of Davies and right-back Matt Doherty, who has missed the last two matches, on Wednesday, Mourinho hinted at further injuries, saying: "Yeah, and we have more problems than that what I'm not going to share.
"You have to wait for tomorrow but we have a little bit of more problems than that."