Spurs fans were left fearing the worst when Romero was replaced by Pape Matar Sarr ahead of the second half on Sunday, with the team trailing 2-0 after a disaster first-half display.
Fellow defenders Djed Spence and Kevin Danso were ruled out ahead of the game, while Micky van de Ven sat out his second game with a niggle.
But Romero told reporters after the game that he was “okay”, with manager Thomas Frank confirming the player has been complaining of an illness.
“[He] pushed through that with a fantastic captain's performance, and struggled a little bit, but we hope it's nothing. We are assessing him. Hopefully he's fine."
The striker was withdrawn late on in the game to spark fresh injury fears, but he confirmed to Sky Sports afterwards that he is “fine”, adding: “I just rolled my ankle, I’ll be fine.”
Frank added soon after: “Clearly also struggled to run. We knew before the game again it would be a big push to play 90 [minutes]. He's not there fitness-wise where he should be, because he's been out for so long. And we've been, in a way, a little bit forced to play him.
“It's pretty evident that he's relatively important for us. Four goals in four games, with him being on his 70-80 per cent of fitness and top sharpness. But imagine City playing without [Erling] Haaland for six months. We've been quite hard-hit with injuries.”