New manager Andre Villas-Boas is in the market for a midfielder but having had an offer - reported to be worth ?27million - rebuffed, doubts remain over whether the Stamford Bridge will return with an improved one before the end of the transfer window.
"Most clubs don't want to talk about players they are interested in but the Modric situation became public," said Buck.
"We did make an offer, (Tottenham chairman) Daniel Levy has rejected that offer and I don't know if it will go any further, we will have to see.
"Andre didn't give us a shopping list but he did tell us where he thought we could improve.
"He did mention some players but it was not a case of 'I want this guy and I want that guy' because it is more than just selecting the players.
"It is whether the player is available, what the price is and every other dynamic that goes with it.
"But Andre is working very well with the board and directly with Roman (Abramovich) in terms of looking at the squad and trying to see whether there is anything that needs to be done."
Chelsea were held to a goalless draw at Stoke in their opening Premier League match despite creating a number of chances in the second half.
And despite the general assumption that the Champions League is what Abramovich really craves Buck insisted domestic honours were equally important.
"The press say the Champions League is a holy grail for Roman and I don't think that is quite true," he told chelseafc.com.
"Andre says that the Premier League is really what he is looking for and that is the one that I always look at because it is a gruelling season and, by and large, the best team wins.
"With the Champions League a lot depends on the draw and other factors so there is a little bit of luck involved, which isn't the case in the Premier League.
"I have never heard Roman say that the Champions League is a holy grail.
"The only thing I have heard him say is that he wants to win the next game.
"Having said that, we haven't won the Champions League so it would be great to win it."
Source: Team Talk
Source: Team Talk