GLASGOW -- Neil Lennon quit as Celtic manager on Thursday after winning five trophies in four years with the Scottish club.
Lennon confirmed his decision to step down after his agent Martin Reilly said the former club captain needed a fresh challenge, and wanted "to look ahead to the next chapter of his career."
Despite winning a third consecutive Scottish league, Lennon had reportedly been considering his position for some time because of uncertainties over the player budget for next season.
"I have supported Celtic all my life and the club will always be part of me. However, I feel the time is now right to move on to a new challenge," said the 42-year-old Lennon, adding he will assist Celtic in the search for his successor.
"As ever, we will need our fans' support, and I am sure they will give the club and the new manager the same great backing which they gave to myself," he told the club's website.
Lennon was appointed manager in 2010 as a replacement for Tony Mowbray, and guided Celtic to three league titles and two Scottish Cups. He also led Celtic to the last 16 of the Champions League and his players claimed a win over Barcelona in the group stage in November 2012.
Lennon is expected to continue his career in England, having been linked to clubs including West Bromwich Albion and Norwich. His agent, however, says Lennon has yet to accept a job offer.
"He has nothing lined up. He just feels now is the time to move on to the next challenge," Reilly said.
As a player, Lennon joined Celtic in 2000 and won five titles in seven seasons, and reached the UEFA Cup final in 2003.
He left the club in 2007 to join Nottingham Forest but returned to Celtic Park a year later as a member of the coaching staff.
Lennon's reign was not without controversy as he received a four-match touchline ban following a spat with then Rangers assistant manager Ally McCoist in March 2011. In other incidents the same year, a letter bomb addressed to the Celtic manager was intercepted by Royal Mail staff in 2011 and Lennon was attacked by a Hearts supporter.
Former Celtic player Henrik Larsson, currently in charge of Swedish club Falkenbergs, is favoured to succeed Lennon.