© Rex Features
The show's stars Blake Lively, Ed Westwick and Leighton Meester are currently filming scenes for the programme in Paris.
Lively, who plays Serena, has now been photographed with Lagerfeld in the French capital, sparking online rumours that the fashion designer will appear in the series.
Glamour reports that the programme's network The CW has not yet commented on the speculation.
Previous guest stars on the series include Lady GaGa and Tyra Banks.
