Essendon are reportedly willing to keep wantaway defender Brandon Zerk-Thatcher on their list if a deal with Port Adelaide for wingman Xavier Duursma fails to transpire.

Both clubs enter the final three days of the trade period with a deal yet to be settled following Zerk-Thatcher's request to move back to his home state of South Australia at the expiry of his contract.

The Bombers have managed a successful off-season exchange window so far through the acquisitions of free agency trio Ben McKay, Todd Goldstein and Jade Gresham, with their plans to bring Duursma to Tullamarine the last remaining piece in their trade period puzzle.

Despite being contracted, Duursma has requested a move to the Bombers and would likely be involved in a deal that sees Zerk-Thatcher head the other way.

The second stage of haggling is likely to have the Power seeking further compensation on top of the addition of Zerk-Thatcher, given the Alberton club would be parting with a contracted and emerging former first-round selection in Duursma.

According to News Corp, Essendon is keen on a straight-player swap that hasn't piqued the interest of Port Adelaide, with the Bombers now said to be threatening to make a move that might see them retain Zerk-Thatcher for 2024.

The Bombers were keen to re-sign Zerk-Thatcher earlier this year, with a three-year offer on the table for the former Sturt backman. The club's acquisition of McKay has helped fill a void in Brad Scott's defence that was likely to be opened up by the impending departure of Zerk-Thatcher.

MELBOURNE, AUSTRALIA - JULY 01: Brandon Zerk-Thatcher of the Bombers is tackled by Willem Drew of the Power during the 2023 AFL Round 16 match between the Essendon Bombers and the Port Adelaide Power at the Melbourne Cricket Ground on July 1, 2023 in Melbourne, Australia. (Photo by Michael Willson/AFL Photos via Getty Images)

The Pre-Season Draft looms, given Zerk-Thatcher's off-contract status, however, other clubs could be ready to prepare bids for the key defender.

The firm stance from both clubs is likely to see a deal between the Power and Bombers, if it comes to fruition, take place on the final day of this year's trade period.

Port Adelaide are needing to settle deals with three other clubs before Wednesday's 7:30pm (AEDT) deadline, with the South Australian club looking to bring in Geelong's Esava Ratugolea, Richmond's Ivan Soldo and Western Bulldog Jordon Sweet.

Ratugolea looms as the club's priority target, however Geelong are also standing its ground after knocking back Port Adelaide's offer of Pick 25 for the forward-turned-defender.

Port Adelaide's draft hand currently reads as Picks 25, 41, 49 and 76 for this year's count as well as two 2024 second-round selections.