Lazio coach Delio Rossi stepped down on Monday after weeks of speculation.
''It wasn't an easy decision, I thought about it a lot,'' the coach said.
''I realised I was no longer at the centre of the Lazio project''.
Former Atalanta coach Rossi, 48, joined the Roman club in 2005 and led it to third-place Serie A finish in 2007 and a win over Sampdoria in last month's Italian Cup Final.
Lazio have ended the last two seasons in mid-table.
Lazio Chairman Claudio Lotito has refused to say who he is looking at as a replacement but 45-year-old Davide Ballardini, who recently quit at Palermo, has been linked to the job.