Rodrigo Bentancur appeared to suffer a serious injury early on in Totteham's Carabao Cup semi-final clash with Liverpool.
The midfielder, who has just returned from a ban, started in midfield for the game, though his night lasted just a matter of minutes before he hit the desk in concerning scenes.
Tottenham started brightly in the game, and were setting up for an attacking corner with Bentancur in the box alongside a number of his other team-mates.
He dived to head Pedro Porro's corner, but appeared to land awkwardly, laying unmoved on the pitch as play continued, with Liverpool goalkeeper Alisson forced into action.
It was then clear, though, that Bentancur would require immediate medical attention, and medics soon rushed over as players urged them over and tried to attend to Bentancur.
The 27-year-old received treatment on the field for nine minutes in total as he left the field on a stretcher to the applause of both sets of fans.
WARNING: Distressing images
Bentancur had missed seven games of domestic action before returning against Nottingham Forest on Boxing Day. He continued to play in the Europa League.
He was handed the ban for a racist remark about Spurs team-mate and captain Son Heung-min, which he apologised for.
Tottenham appealed the decision, with the player also fined £100,000, but thayt was rejected and they had to make do without him for seven matches. He also recently served a Premier League suspension for yellow card accumulation.
He now, however, appears set for a lengthy spell on the sidelines again following the incident on Wednesday. It has not been made clear what the issue was.
'We're all with you, Lolo,' Spurs' official X account posted.
He left the field with 15 minutes on the clock, having initially gone down after six minutes. The substitution was not a concussion substitute - and he put his thumb up as he was taken off.
The midfielder also had a blanket placed over him and was wearing an oxygen mask, though was pictured with his eyes open.
If he misses more matches, it adds to Tottenham's current injury crisis, which has seen a number of first team players miss game time.
First-choice goalkeeper Guglielmo Vicario has been out of action since the end of November after undergoing ankle surgery, while Spurs have also been torn apart defensively.
They are currently without first-choice centre backs Sergio Romero and Micky van De Ven, while back-up option Ben Davies is also missing.
Left back Destiny Udogie, meanwhile, is expected to be out until February with a hamstring issue.