Chelsea manager Roberto Di Matteo has admitted he fears Frank Lampard and Ashley Cole could quit Stamford Bridge.
The Chelsea duo will be free to discuss personal terms with other interested clubs in January if they fail to agree terms on a new deal with the Blues, as both of their current contracts expire at the end of the season.
Chelsea are thought to be keen to extend their deals, but are only willing to offer the pair one-year extensions, leading to speculation the likes of Manchester United, Real Madrid and Paris St Germain could swoop.
And when asked if he feared either Lampard or Cole could sign agreements with another club when the transfer window reopens, Di Matteo said: "Yes, but that's the world of football. That's how you live in this world, in this industry.
"We had the same last season with some players and, at the end of the day, we all have to be professional and try to do our best, even though maybe the contract is not sorted out."
31-year-old Cole and 34-year-old Lampard have been fixtures at Stamford Bridge for the last half a decade, and have formed an integral part of one of the most successful Chelsea sides of the modern era.
The Blues slipped to their first Premier League home defeat of the season on Sunday, losing 3-2 to Manchester United, but Roberto Di Matteo's side retain the Premier League lead by one point.
Juan Mata and Ramires scored for Chelsea to rescue a two-goal deficit at Stamford Bridge, but the Blues were reduced to nine men after Fernando Torres and Branislav Ivanovic were sent off.
Two-men light, Chelsea faced almost thirty minutes of constant pressure as they looked to safeguard a point, but Manchester United substitute Javier Hernandez sealed all three points with a late winner for Sir Alex Ferguson's side.
Chelsea face Manchester United again on Wednesday in the Capital One Cup.