Swansea have earmarked Duff as the man to replace Martin with the club having already held discussions with the 45-year-old following an approach. Talks are said to have gone well and are now at an advanced stage.

Martin's move to the south coast had been held up over a compensation wrangle with Swansea lasting several weeks.

With his departure now confirmed, Swansea are closing in on a move for Duff, who took Barnsley to the League One play-off final last month.

Swansea return to pre-season training on Friday and are due to fly out to Spain for a pre-season training camp on Sunday.

Duff, who is one year into a three-year contract, has a release clause in his deal. To activate it will reportedly cost £500,000.

The fee is not thought to be an issue for the Swans.

Swansea had lined up Martin's former assistant Chris Davies as their preferred choice to replace Martin, but he is set to join Ange Postecoglou's new-look coaching team at Tottenham Hotspur.

Plymouth Argyle boss Steven Schumacher was another contender, but he elected to stay in Devon, while another target in coach Gregg Berhalter recently re-joined the US national team - prompting a rethink and a move for Duff by the Swans.

Swansea City close in on move for Barnsley FC head coach Michael Duff after Russell Martin's departure to Championship rivals Southampton is confirmed