Despite seeing two bids fail for the Croatian earlier this summer, the Blues are still keen to take the 25-year-old to Stamford Bridge but face a real battle to persuade Spurs to sell.
Having seen his team held to a 0-0 draw at Stoke on Sunday, Andre Villa-Boas admitted he needs further new faces and it's in the middle of the park where he wants new additions.
Although chairman Bruce Buck said he was "unsure" over a further bid for Modric, his manager has left the board in no doubt as to where the team needs strengthening.
Villas-Boas said: "The sense of urgency in midfield is there. We play 4-3-3, we have a squad of 25. For you to prepare for a game, you need at least six midfielders. We only have four."