Up in the directors’ box, Todd Boehly and Behdad Eghbali were deep in conversation. Chelsea’s co-owners had witnessed a rare thing: a goal, a win, flashes of positivity. But it so easily could have gone in a different direction. Chelsea were a bag of nerves when they were trying to hold on to their slender lead during the dying stages and, although Graham Potter was in no position to turn down the points, he will know that his side must show far conviction at both ends of the pitch when they host Borussia Dortmund in the last 16 of the Champions League on Tuesday.