Rob Burch.
The Imps boss watched his side slip to their third successive defeat at the weekend losing 2-1 at Chesterfield to leave him clamouring for a watertight backline.
Again, Lincoln paid the price for a poor start, falling behind to Dominic Green's howitzer before Barry Conlon put them further in front just after half-time.
Moses Swaibu's deft lob, his first goal for the club, pulled City back into the game, but Sutton admitted his side had given themselves too much to do.
"You can't give teams a two-goal start," he said. "Although our performance was much better than Tuesday night, when we were bitterly disappointing, we actually did okay at Chesterfield.
"But we have to go back to being mean and stingy and try to keep clean sheets. The second goal killed us really, and it came from the third phase of a corner.
"That has been a particular problem for us. Football is all about small details and defending set-pieces is a massive part of the game.
"We don't score from many and we concede too many. I'm afraid it's one of those things where people want to go and head it or they don't.
"Some people react quicker than others and at the moment we simply aren't reacting."