Southampton have confirmed that Simon Clifford, Sir Clive Woodward's right-hand man, has left the club.
The club earlier refused to comment on reports Clifford, appointed by Woodward as head of sports science at the start of the season, had been sacked.
"It was his decision and I'm very sorry to see him go," said Woodward.
Clifford was said to have upset Southampton players and officials after an article which suggested footballers do not train hard enough.
"I have read speculation that I am supposed to have sacked Simon but nothing could be further from the truth," added Woodward.
"I enjoyed working with him and I still believe he has a great deal to offer the game."
The 34-year-old Clifford - also the owner of non-league side Garforth Town and a successful football coaching company - blamed his other commitments for his early departure from St Mary's.
"I was very excited about coming to Southampton and I was hoping to work with Clive for many years," said Clifford.
Woodward had praised Clifford's coaching skills
"But unfortunately it has proved impossible to combine that with my other projects.
"I believe the club can achieve great success under (Southampton chairman) Rupert Lowe's leadership and I wish him, Clive, Harry Redknapp and the players all the very best for the rest of the season.
"They have a great set-up there and I firmly believe they can win promotion and push on strongly in the Premiership."
Woodward recently gave an interview in which he outlined Clifford's role at Southampton.
"We are getting him to work with individual players, some of the younger players, just on one-on-one skills," Woodward told The Observer in October.
"These kind of sessions will go nowhere near the team sessions. You've got to leave them in stone.
"But outside of that you've got evenings, mornings, afternoons. I think history will show he will be a major acquisition for the club."