Watford have taken Estonia international defender Andrei Stepanov on trial with a view to a permanent deal.
The Hornets are short of defensive options with captain Jay DeMerit currently struggling with a knock, and manager Brendan Rodgers is keen to run the rule over the 30-year-old.
Rodgers said: "He is an international and a very experienced player."
He added: "We are having a look at him for a couple of days with a view to something between now and the end of the season to provide cover for our centre-halves.
"We are just taking our chances in this period to look at him and it may go from there."
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