Watford have activated a clause in their ground share contract with Saracens, which could spell the end of rugby being played at Vicarage Road, reports BBC Sport. Sarries have used Watford's ground for their home games since 1997 and the current deal lasts until 2017.
But Watford have used a "break clause" which would see Saracens leaving Vicarage road by 1 June, 2011.
Hornets chief executive Julian Winter has not written off the possibility of the two clubs reaching a new deal.
Winter said: "The football club has also agreed to a three-month period of extended negotiation to enable Saracens time to decide upon their preferred future home, one of which could still be Vicarage Road."
A club statement added: "Watford Football Club remains hopeful that both parties can negotiate a new lease which sees Saracens become a partner in the improvement of the Vicarage Road facilities and pitch."