Edy Reja has left Lazio after just six months in charge, saying some fresh blood is needed to boost the club's fortunes next season.
The 68-year-old has chosen not to extend his contract, which expires at the end of the month, bringing an end to his second spell on the Biancocelesti bench after he was unable to guide them back into Europe.
"Even before the season had ended, the president asked me to continue and I told him that I felt a cycle was closing," Reja said at a news conference in Rome on Thursday. "I'm sticking by my conviction -- a new coach who can bring new enthusiasm to the club is now needed."
Reja was lured out of retirement to replace Vladimir Petkovic in January after the club lost faith in the Bosnian coach, who had already reached an agreement to take over as coach of the Switzerland national team after the World Cup.
President Claudio Lotito has been unable to convince the man who led them into the Europa League two years in a row between 2010 and 2012 to stay on and try to qualify again next season.
"It's only right to change now that this cycle has come to an end," Reja continued. "The whole atmosphere needs to change. I get the feeling the club are working on this in the right manner.
"We got some good results of late, but we didn't qualify for Europe. That was a huge disappointment and maybe if we'd qualified, my feeling would have been different.
"All we needed to do was beat Torino and the scenario would have been different. Maybe then we would have been able to attract different players to Rome.
"My affection for the club and the president remains, however. If you've never coached in Rome, then you cannot say you've been a coach. It has been an extraordinary experience and I hope I did a good job.
"I'm sorry for those people who didn't show much recognition for what I did, but I'd like to thank all the rest."
Stefano Pioli, who was sacked as coach of relegated Bologna only three days after Reja took charge of Lazio, is rated his most likely successor, although consideration has also been given to Simone Inzaghi, who led the club's youth team to the semifinals of the youth championship this season.
Massimiliano Allegri has already ruled himself out of the running.
Meanwhile, the Biancocelesti on Thursday announced that club captain Stefano Mauri had extended his contract by a year.
The 34-year-old former Italy international missed half of last season due to a ban for his role in a match-fixing scandal and made just 12 appearances in Serie A last term, scoring four goals.