It's understood the off-contract Appiah is joining Incheon United for pre-season, with the country's top-flight to begin in March.

The pacy 25-year-old winger will leave having scored two goals in 38 league appearances since rejoining the Mariners two seasons ago, where he played in the club's title-winning youth team of 2011-12.

In between he had stints at the Western Sydney Wanderers and Wellington Phoenix.

Appiah's departure is another loss for the Mariners' attacking stocks after homesick Spanish striker Asrubal was released earlier this month.

The transfer fee does give the club more money to play with in their hunt for a No.9 to improve the ninth-placed side's league-low goal return of 18.

However, with Wednesday marking the final day of the January transfer window, they will have to act fast.

Coach Paul Okon had been chasing Socceroos representative Apostolos Giannou, of Guangzhou R&F but was outbid by Cypriot first-division outfit AEK Larnaca.

In a boost for Okon's defensive options, Jacob Poscoliero returns to the club after his transfer from the Perth Glory.

The 27-year-old defender has signed a deal until the end of the season and will be considered for selection when the Mariners host the Wanderers on Sunday.

After mnaking his A-League debut for the Mariners in 2014, Poscoliero played 47 games before heading west to join the Glory at the end of last season.

"I'm thrilled and delighted to be able to put a Mariners jersey back on," Poscoliero said.

"I can't wait to get back to training - I've really missed both the coaching and style of play here at the Mariners and I am very grateful to be given this opportunity to play under Paolo again."