Modric scored in the 1-1 draw at West Bromwich Albion yesterday but received a kick on the fibula he broke last season and his manager is anxiously awaiting the results of a scan.
"It doesn't look great. If he has got another break, you're talking months again.
"When he plays, he opens the door. If he had played in our defeat to Wigan we would have won, he would have opened them up with a bit of magic. He is a fantastic player.
"He is comfortable with the ball and if you can handle the ball, can pass and keep it well, you have a chance. I am just hoping it is good news for a change. Defoe has had the ankle operation and he is out for 12 weeks and Dawson is another one."