Derby County have taken former Celtic and Hibernian centre-back Efe Ambrose on trial.
The 30-year-old free agent has been training with the Rams, having triggered a clause to leave Scottish Premiership side Hibs in January.
Manager Frank Lampard had previously said that strengthening the defence was “crucial” if they are to maintain their Championship promotion challenge.
“Nothing is signed and sealed yet,” Lampard said on Friday.
“Efe hasn’t played a competitive match since the end of December. It was good for us to have a look at him in this way. If a deal is done, we will let everybody know.”
A season-ending injury to Curtis Davies left Lampard without his captain, and further injuries at the back prompted the former England midfielder to say in January that first-choice duo Richard Keogh and Fikayo Tomori needed “help”.
“We know we needed a centre-back,” Lampard added. “I felt we would get someone but that didn’t happen. Efe is here outside of the window and if he can come in then great.
“If not then we have two regular centre-halves that have been playing fantastically well all season.”