Arsenal are reportedly tracking Serbian international defender Neven Subotic.
The 21-year-old centre back originally appeared on the radar in North London back in April, with Arsenal boss Arsene Wenger hoping to land the player before the World Cup.
Subotic showed his class during the tournament in South Africa, building on his reputation as one of the best young defenders in Europe alongside Nemanja Vidic.
A Bundesliga regular at Borussia Dortmund, Subotic joined the German side from Mainz 05 in 2008 and has since made 78 appearances in all competitions.
Die Borussen have constantly warned off potential suitors over a bid for the player, but Arsenal, Manchester City, Chelsea and Real Madrid are all reported to be interested in a potential move for the player.
Frenchman Wenger had hoped to bring the player to the Emirates for a fee in the region of £12 million, but the Westfalenstadion club valued the player at £20 million following his performances on the world's biggest stage.
Despite signing Laurent Koscielny and Sebastien Squillaci in the summer, the Arsenal boss is still thought to be keen to add another high quality central defender to his ranks.
The asking price might be a potential stumbling block for the Gunners, who could look to negotiate or offer a player-plus-cash deal in their efforts to sign the player.