- Adam Johnson sacked after pleading guilty to one count of sexual activity with a child
- Johnson also admits to one count of grooming, denies two further allegations
- Trial to begin in Bradford, England on Friday
"In light of Adam Johnson's guilty pleas, the club has today terminated his contract with immediate effect," a statement on the club's website read Thursday. "The club will make no further comment."
The 28-year-old's sacking follows his appearance at Bradford Crown Court in the north of England Wednesday where he denied two further child sex allegations, but admitted to another count of grooming a girl under the age of 16.
Johnson's trial for the two contested charges begins Friday.
The footballer is being defended by Orlando Pownall, who last year successfully defended New Zealand cricket captain Chris Cairns -- acquitted of perjury and perverting the course of justice -- while Kate Blackwell, who helped prosecute serial killer Harold Shipman, is leading the case for the prosecution.
Sportswear firm Adidas also confirmed in an email to CNN Friday that it had terminated its sponsorship deal with the player in light of "his guilty pleas entered earlier this week."
Johnson was arrested in March 2015 and was initially suspended by Sunderland before returning to the team a fortnight later.
He played and scored for the team during last weekend's 2-2 draw with Liverpool.
Sunderland manager, Sam Allardyce, initially told reporters Thursday that Johnson would not be included in squad to face Manchester United Saturday.
While playing for Manchester City between 2010 and 2012, Johnson won the Premier League title and the FA Cup.
He last played for England in August 2012.