The former Juventus and Atalanta BC defender has already spent a bit of time in the infirmary this season with a toe injury, which he sustained in the 4-1 win over Aston Villa on November 3.
Romero sat out Spurs' 3-2 defeat to Galatasaray in the Europa League last Thursday, but he recovered in time to play the full 90 minutes in the weekend's shock 2-1 loss to Ipswich Town.
Having quickly battled back from that toe problem, Romero was given the green light to link up with the Argentina national team and started their World Cup 2026 qualifier against Paraguay on Thursday.
However, the 26-year-old did not reappear for the second half of that defeat, being replaced by Marseille's Leonardo Balerdi at the break, and the world champions conceded for the second time in the match just two minutes after his withdrawal.
Scaloni comments on Romero withdrawal
According to 11 Noticias, Romero had to have pain-killing injections to be able to play against Paraguay, and he is now a huge doubt for the showdown with Peru next Tuesday.
It is believed that the centre-back's latest problem is also on his right foot, where he previously suffered his toe problem, and Scaloni only offered a brief update when asked by the media after the game.
"Balerdi came in because 'Cuti' [Romero] couldn't continue," Scaloni said, and the defender is currently believed to be undergoing assessment to determine his availability for next week's game.
Romero's latest concern comes just over a week before Ange Postecoglou's side square up to Manchester City in the Premier League on November 23, hoping to inflict a fifth straight loss on Pep Guardiola's side.
The Lilywhites then continue their Europa League campaign at home to Roma - who recently announced the return of Claudio Ranieri as their new head coach - before starting December with a London derby at home to Fulham.
Who could replace Romero for Man City clash?
Postecoglou is no stranger to being without both of his main centre-backs at once, as he had to work around the absence of Romero and Micky van de Ven last season when the former was suspended and the latter injured.
If Romero's injury this time around proves to be at least moderately severe, history could repeat itself for the Australian, who is already missing Van de Ven due to another hamstring issue.
The former Wolfsburg man is believed to have a slim chance of coming back for the trip to the Etihad, but December is seen as a more realistic date for Van de Ven to return, meaning that Ben Davies may have to be drafted in alongside Radu Dragusin.
That was the case in the Europa League defeat to Galatasaray, although summer signing Archie Gray has also dabbled in centre-back duties since joining from Leeds United and is an alternative option.
Richarlison and Wilson Odobert are also sidelined with thigh problems for Tottenham, while Rodrigo Bentancur is believed to be facing a seven-game ban for comments made about Son Heung-min, but Timo Werner and Mikey Moore should be back from illnesses in time to face Man City.