Title-chasing Monaco have spruced up their defence by bringing in left-back Elderson from Portuguese club Braga.
The Nigerian joins on a four-and-a-half-year contract and returns to French football after three years at Braga, having previously played for Rennes.
Elderson, widely know by his nickname rather than his birth name Uwa Echiejile, is a full Nigeria international with 38 caps and turns 26 on Monday.
He told Monaco's website: "I am very happy and very proud to return to France with a club like Monaco, who are one of the best in Europe and who possess great repute in Africa since George Weah emerged there.
"Moreover, excellent Nigerian players have worn the short, like Victor Ikpeba and Lukman Haruna, and I'll give the best of myself to succeed them as well as I can."