Cesar Azpilicueta said Chelsea should have won by a greater margin at Malmo after only securing a 2-1 victory in the first leg of their last-32 Europa League tie.
Goals from Ross Barkley and Olivier Giroud put Maurizio Sarri's side on track to end a run of four consecutive away defeats in all competitions without scoring.
But Mateo Kovacic's error let in Anders Christiansen to score a late reply for the Swedish side that leaves work to do for the Blues in next week's return leg.
Chelsea showed a vast improvement from their 6-0 humiliation at Manchester City in the Premier League on Sunday, but Azpilicueta complained about the lack of a clean sheet from their trip to Swedbank Stadion.