Sunderland chief executive Margaret Byrne said on Tuesday that the club sacked manager Paolo Di Canio in order to avoid becoming "cut adrift" at the foot of the Premier League.
The 45-year-old Italian was fired on Sunday after Sunderland drew one and lost four of their opening five league games, culminating in a 3-0 defeat at West Bromwich Albion.
Reports in the British media suggest Sunderland's players were unhappy with the outspoken Di Canio's methods, but Byrne said he was removed purely to improve the club's chances of staying up.
Writing in the match-day programme ahead of Tuesday's League Cup third-round tie with Peterborough United, she said: "Whilst the focus is on tonight's game, I know how disappointed each and every supporter was after Saturday's result at West Brom. Everyone at the club felt the same disappointment.
"After Paolo saved us from relegation last season, we gave him an opportunity to take the club forward this season.
"When it became obvious it wasn't working, we had to take the decision to part company with him. We felt it was better to do this now as we ran the risk of being cut adrift at the bottom of the Barclays Premier League.
"We wish Paolo and his staff well for the future."
Development coach Kevin Ball has been put in temporary charge of first-team affairs, with former Brighton and Hove Albion manager Gus Poyet the favourite to succeed Di Canio on a permanent basis.