Brandon Marshall has admitted that he is "shocked" by the Chicago Bears' progress in the first week of training camp.

The NFC North side have a new head coach, offensive coordinator and defensive coordinator heading into the 2013 NFL season.

The wide receiver told the Bears' official website: "Usually when you change your offense up, or change anything up, it takes time, and it's going to be a work in progress throughout this year, throughout the next few years just to catch up with some of the great offenses around the league.

"But I'm shocked to see where we're at today. We're putting in extra work, [quarterback] Jay [Cutler] is really leading us and holding us accountable, and I think that's the reason why we're making big jumps every single day.

"Our number one goal is to be the best [receiving] group in the league. We don't get a lot of credit. They actually say we're one of the weakest units on our team."

The Bears have made the playoffs just once in the last six seasons.