The Red Devils will be without first-choice option Luke Shaw for a number of weeks as the England international recovers from a serious muscular injury.
In addition, Shaw's lieutenant Tyrell Malacia is yet to make a competitive appearance this term due to a muscle issue, which is likely to keep him out until after the international break.
Prior to Shaw's diagnosis, Man United sanctioned a loan move to Ipswich Town for the out-of-favour Brandon Williams, and Diogo Dalot filled in on that side against Nottingham Forest.
Erik ten Hag could also deploy Alvaro Fernandez on that side, as the 20-year-old will likely stay at the club given Shaw's layoff, but he lacks experience at the top level of English football.
As a result, Ten Hag has confirmed that his side will scope out left-back options before the September transfer deadline, and a loan deal for Chelsea's Marc Cucurella is supposedly being discussed.
Alternatively, the Manchester Evening News claims that Spurs outcast Reguilon is also under consideration, as there is no indication that he will be able to reignite his Tottenham career.
The former Real Madrid man became a Europa League winner with Sevilla in 2020 before joining the Lilywhites in a £25.7m deal, but he has played just 67 times for Spurs over the past three years.
Reguilon boasts two goals and nine assists for the North London giants, but he endured a challenging loan spell with Atletico Madrid last term, failing to score or assist in 12 matches.
However, the Spaniard's time at the Wanda Metropolitano was also hampered by health problems, and he was given the chance to prove himself under Ange Postecoglou in pre-season.
Since the start of the Premier League campaign, though, Destiny Udogie has cemented his place as Postecoglou's first-choice left-back, while Ben Davies also sits above Reguilon in the pecking order.
As a result, the 26-year-old is yet to make a Premier League matchday squad under the Australian, and Spurs are believed to be open to offers for the left-back before Friday's deadline.
Reguilon is only under contract with Tottenham until the end of the 2024-25 season, but the report adds that a move could potentially be scuppered by his salary demands.
Man United apparently weighed up a move for Reguilon in 2020 after his Europa League success with Sevilla, but the Red Devils instead brought Alex Telles to the club from Porto.
The Brazilian's switch to the Theatre of Dreams did not work out as intended, though, and he left for Al-Nassr in a £4m deal last month.