The 26-year-old had missed four successive matches with a toe problem, including the 1-0 loss to Bournemouth in midweek, but he was cleared to return to the XI for the visit of the Blues.
Romero reformed his regular partnership with Micky van de Ven, who made a surprise early return from his thigh problem, but Postecoglou's decision to bring the former back in backfired spectacularly.
With only 15 minutes on the board at the Tottenham Hotspur Stadium, Romero appeared worse for wear after a backheel, and the South American quickly had to make way for Radu Dragusin.
While the exact nature of Romero's issue remains unknown, Postecoglou will be expected to deliver an update in his post-game press conference, where he may very well also be grilled on his decision to bring the Argentine back into the XI.
Spurs are already coping without Guglielmo Vicario, Richarlison, Wilson Odobert, Ben Davies and Mikey Moore due to injury and illness, while Rodrigo Bentancur is serving a lengthy domestic ban for an offensive comment towards Son Heung-min and South Koreans.
Quickfire strikes from Dominic Solanke and Dejan Kulusevski propelled Spurs into a two-goal lead against Chelsea, before Jadon Sancho pulled one back for the Blues.
Written by
Ben Knapton