Kenedy opened the scoring forty seconds into the game, taking advantage of an open Norwich defence to fire the ball into the net.
Costa scored with a neat finish that looped over the stranded Norwich goalkeeper John Ruddy and gave the Blues a two-goal advantage going into halftime.
The goal was later revealed to be offside, with the linesman admitting to Norwich boss Alex Neil afterwards that he understood he had made the mistake.
Speaking in his post-match press conference, Hiddink was slightly critical of his players, who he felt should’ve finished the game early in the game considering the chances they had.
I think we were a bit sloppy in finishing off in the first half. We had a splendid start through Kenedy, I haven’t seen it on the replay but I think it was a beautiful goal.
Chelsea now have a busy period, with the Blues taking on Stoke at the weekend before taking on Paris Saint-Germain in the second leg of their Champions League game, with Chelsea currently 2-1 down on aggregate.