Dijon say they have signed Papy Djilobodji for his athleticism and aerial ability.
The 28-year-old has moved to the Ligue 1 side on a season-long loan deal.
With the Senegalese centre-back out of favour under Black Cats boss Simon Grayson, the club have decided to move him on in a temporary deal to free up much-needed wages.
The Black Cats remain hopeful of making additions before the 11pm deadline. Djilobodji will now look to rebuild his career in France, where he spent five successful years at Nantes.
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Sebastien Larcier, Dijon's head of Recruitment, said: "He is a left-footed, athletic and powerful defender, performing well in the aerial field, which sometimes fails us. His experience of the high level will also be interesting."
Club President Olivier Delcourt said: "It was a priority for several weeks, we are therefore very pleased to have finalized this transfer. Papy has undeniable qualities and will bring us his experience."