Campbell admits Fabregas' departure from the Emirates could be disastrous for the club.
The defender said: "It's going to be tough. When he first got to the club at Arsenal I knew he was going to be an international straight away.
"His temperament, the way he trains, everything about it. You can't teach that - the way he conducts himself. You knew when he came into the club he was going to go a long way.
"The vision, everything. He's had a fantastic season. How he goes about training, being about the club.
"He's a great captain, he's taken it on. He's a great lad as well.
"Fabregas really makes the team tick. The number of goals he has scored this season has been fantastic."