Chelsea have turned down Steve Clarke's resignation as assistant first-team coach following an approach by West Ham to take him to Upton Park.
But the Hammers, who named Gianfranco Zola as their new manager on Thursday, are confident Clarke will be his number two, BBC Sport understands.
It is thought negotiations over compensation are ongoing.
Chelsea said West Ham made an approach for Clarke, 45, but they denied permission to speak to him.
"We have not accepted his resignation. Talks are continuing," read a Chelsea statement.
Clarke joined the Stamford Bridge outfit as a player in January 1987 and the defender helped the club win the FA Cup, League Cup and European Cup Winners' Cup before retiring in September 1998.
He went on to join Ruud Gullit as his assistant at Newcastle and had a brief spell as caretaker manager at the Tyneside club after the Dutchman's exit in August 1999 before working under Sir Bobby Robson at St James' Park.
The Scot returned to Chelsea - where Zola enjoyed a successful stint between 1996-2003 - and has assisted recent Chelsea managers Jose Mourinho and Avram Grant as well as Luiz Felipe Scolari.
Scolari held talks with Clarke on Wednesday and said he would give him more responsibility.
"On Thursday I invited Steve to my house and we discussed this situation with West Ham, Chelsea and the life of Steve - his project," said Scolari.
"Steve is very important for me and Chelsea. He is a man that is a point between me and the players and me and the staff. He knows very well Chelsea, the England players and clubs.
"All people have projects in life. Steve wants to fly it alone in the future. For me, I understand because I am a professional for football."
He added: "We try to say no, look maybe you follow this, but Steve is thinking this way. I don't agree, but I am happy with Steve, as a person and a coach. I wish him all the best.
"I don't know what happened in the night but when I came here in the morning I heard he had resigned."
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Scolari expects him to go and re-join Zola and said: "Now I have been told he is going I am sad but I understand Steve.
"I don't agree with his decision but I am happy for him because I like Stevie.
"I like him as a person and as a coach and I wish him all the best."
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