Defoe is unavailable for the FA Cup visit of Bristol City as he was absent from training after phoning in sick and Adams revealed the club have sent a doctor to the striker's Hertfordshire home to assess his condition.

The England forward has become one of the most sought-after players this transfer window with Aston Villa, Manchester City and Tottenham all vying for his signature.

Defoe, 26, held a meeting with executive chairman Peter Storrie and Adams last week when he signalled his intentions to walk out on the FA Cup holders less than 12 months after joining them from Spurs for £7.5million.

Adams said: "Jermain is not very well and a doctor is going round his house to assess him. Peter Storrie had a meeting with him last Wednesday, which I sat in on, and Jermain expressed a desire to leave.

"I think Peter is talking to a few clubs about him but the final decision will be mine and I have a price in mind of what I think he is worth.

"He is a superb player and a great goalscorer but I have not yet made up my mind whether or not I am going to sell him.

"I have to make a call on that like I had to with Lassana Diarra when Real Madrid came knocking.

"If I wanted to play him against Bristol City I could because he is still a Portsmouth player but it looks as if his illness has taken that out of my hands."

In Defoe's absence Peter Crouch will assume a lone role upfront as Portsmouth begin their defence of the FA Cup title they won at Wembley in May.

Adams was Harry Redknapp's assistant on that day but has a memorable cup pedigree behind him having won the trophy three times with Arsenal but he also suffered the embarrassment of a third-round exit to Wrexham in 1992.

Adams said: "I have experienced everything in the FA Cup, I have been knocked out at Wrexham, I have been knocked out in every round and I have won it but in every year I have won it we were very lucky.

"Just look at Brian Clough who was a fantastic manager but this was the only trophy he never won. I have won it as a player and a coach so I would love to win as a manager but it is a very difficult competition and you have to earn the right to lift it.

"It is also a very special competition but one which can take you up and bring you down. We are the holders and we do not want to go out in the third round."

Adams has only 18 fit players to choose from for the visit of Bristol City with defender Martin Cranie set to make his first start for the club since August 2007 after a prosperous four-month loan spell at Charlton.

Defenders Glen Johnson and Younes Kaboul are injured and Sol Campbell could be rested while midfielders Papa Bouba Diop, Richard Hughes and John Utaka are also out.

Adams added: "Because of the problems we have with injuries there will be an opportunity for other people. I got my chance at Arsenal because David O'Leary was injured.

"Martin has been to Charlton for the last six months and done very well so is a player who needs an opportunity. Football is a squad game, I have every confidence that my squad is good enough."