Gianfranco Zola has resigned as Birmingham manager after just four months in charge following Monday's 2-0 Sky Bet Championship defeat at home to Burton.
The 50-year-old Italian was appointed in December after the controversial sacking of Gary Rowett, but has overseen just two wins in 22 league games.
"Gianfranco Zola has this evening resigned as Blues manager,'' Birmingham confirmed on Twitter.
Monday's loss left the midlands club three points above the relegation zone with three games remaining.
Goals in either half from Lloyd Dyer and Lucas Akins sealed a double for Albion over the Blues, with home fans chanting "we want Zola out" towards the end of the match.
The 50-year-old Italian, who took up the reins in December following the controversial sacking of Gary Rowett, faced the media after the match to express his sorrow that he could not fulfil the club's expectations.
"I sacked myself," said Zola, who oversaw just two wins in 22 league games. "I decided to give in my resignation. I am sorry because I came to Birmingham with huge expectations. Unfortunately the results have not been good and I take full responsibility.
"It is not that I like quitting, but Birmingham deserves better. If I feel I cannot help the players, why stay? If I cannot help the team, it is better I leave and let someone else do that.
"I feel very bad and very sorry. We worked with a lot of meaning, but unfortunately it didn't produce the results. It is all very disappointing."
Zola insisted the reaction of the crowd did not have any bearing on his decision.
"I cannot blame the supporters," he said. "The club's position is not secure and they are frustrated and I can understand their feelings.
"They chant and say they want me out. It is a little harsh. We have made some mistakes, but we have worked hard for the club.
"I was totally convinced that what I was doing was right. Unfortunately the results were not good."
Zola was appointed by Birmingham's owners, Chinese firm Trillion Trophy Asia Limited, two days after the departure of Rowett, with the club lying seventh in the table.
TTAL had completed its takeover at St Andrew's the previous October, and club director Panos Pavlakis said at the time that Zola was a good fit as the Blues wanted to "move in a new direction."
But, since Zola's arrival, the club have maintained a steady slide down the table, winning only twice -- against Fulham and at Wolves in February. Defeat to Burton extended their winless league run to nine matches.
Zola, sacked in his previous managerial job after just one season with Qatari side Al-Arabi, has also had spells in charge of West Ham, Serie A side Cagliari and Watford.