Burton boss Gary Rowett cast his eye over a handful of trialists in a behind-closed-doors friendly against Derby this week.
Rowett, who is looking for players to sign on loan deals until the end of the season to help maintain Albion's promotion challenge in League Two, saw his side lose 9-1 at the Rams' Moor Farm training ground on Tuesday afternoon.
The Brewers did not want the names of those on trial revealed for fear of alerting other clubs, but Rowett was looking at two centre-backs and a couple of forwards.
Two of the quartet were players from a higher level than League Two, one trialist was from non-league and one from overseas.
Rowett revealed: "I don't think it's right to name names, especially those of players who are currently contracted to other clubs.
"We are looking to strengthen this month and this was just an opportunity to have a look at a few players who might fit the bill.
"Some of the players we were looking at struggled, but then so did some of our own because it was such a strong Derby side so it wasn't easy for anyone to come in and impress."
The Rams included the likes of Theo Robinson, Nathan Tyson, Mason Bennett - all of who scored twice in the friendly - and Jamie Ward, who also got on the scoresheet.
Jimmy Phillips scored Burton's consolation goal and the midfielder is nearing full fitness after missing the first half of the season with a broken foot.