Chelsea fans blame ticket prices for the empty seats against Rosenborg on Tuesday night.
With adult prices at £36, even after a reduction, many fans claim tickets are too expensive.
Alex Jones, chairman of the Shrewsbury and Mid-Wales Supporters Club, told The Sun: "Chelsea must lower ticket prices. There just isn't enough attractive football on show.
"For me and a few others, the sale of Arjen Robben was a black day.
"When he played he was so exciting and really lifted the crowd.
"The players we have brought in just aren't up to that standard."
Fellow supporter Cliff Lee said: "The football just isn't good enough to charge your average fan that much cash.
"I'm glad I didn't go to the Rosenborg game. I nearly switched over to watch Liverpool we were that bad."