Karpin admitted the Premier League leaders had put terror into the Russians before leaving the capital with a comfortable 2-0 win.
He said: "After I spoke to the players in the dressing room I realised they were a bit afraid to play Chelsea in the second half.
"We lost this game because we lost the first half psychologically. We came out fighting in the second half but it wasn't enough."
Spartak visit Stamford Bridge in a fortnight and Karpin added: "I'm going to show the players the DVD of the first and second halves ahead of the game in London and they can draw their own conclusions.
"We're not giving up on the match in London, we'll go there to try and play well and get points."