Tottenham are increasingly concerned that Jan Vertonghen could be out injured for two months - a longer period of absence than originally expected.
The Belgium international was expected to be absent for four to six weeks after a hamstring injury forced him off during Tottenham's 2-0 victory against Huddersfield on September 29.
But the setback appears to be worse than first thought and the former Ajax defender will be assessed this week. Spurs are concerned he may not return for the remainder of the Champions League group stage, which ends on December 11.
Mauricio Pochettino's assistant Jesus Perez indicated last week that Tottenham would be able to give a more specific time frame on Vertonghen's recovery after a scan.
If Vertonghen is confirmed to be out for two months then he could miss up to eight Premier League matches, including fixtures against Manchester City, Chelsea and Arsenal.
Davinson Sanchez has deputised in his absence although Tottenham appeared to miss Vertonghen as they lost 4-2 to Barcelona in the Champions League last week.
Vertonghen has been left out of Belgium's squad for their UEFA Nations League meeting with Switzerland and the friendly against the Netherlands.