But the Croatia midfielder has vowed to be back to his best by the end of the month, blaming a spell on the sidelines with a leg injury for his lack of "rhythm".
Modric, who is currently on international duty, told his club's official website: "For me, I'm a little out of rhythm.
"I've had a couple of injuries this season and I'm not yet back into my rhythm but, in a couple of games, I'll settle down and play better.
"I just need to be fitter. It's been hard for me because I've had a couple of injuries but in a couple of matches I'll be back into full shape."
Modric, 25, has been overshadowed in recent weeks by new team-mate Rafael van der Vaart, who has established himself as Spurs' new talisman since signing from Real Madrid.
Modric is delighted by the impact made by the £8million man, adding: "Rafa is an exceptional player and he's showed that since he came to the club.
"He's a great signing. He's played at great clubs: Ajax, Hamburg, Real Madrid, and I think he can give more quality to the team."
Manager Harry Redknapp revealed after Van der Vaart's arrival that he felt the Holland midfielder and Modric would complement each other perfectly.
Modric agreed, saying: "It's not hard to play well with that kind of player and I'm happy he's here with us."