Arsène Wenger has strengthened his Arsenal squad impressively this summer, but the sale of Thomas Vermaelen to Barcelona has reportedly led him to target one more signing before the close of the transfer window. Vermaelen’s exit leaves 19-year-old recent arrival from Southampton Calum Chambers as the main backup to first-choice pairing Laurent Koscielny and Per Mertesacker at center-back.

According to the Daily Mirror, the man Wenger has identified to replace Vermaelen is Greece international Kostas Manolas. The 23-year-old Olympiakos man impressed at the 2014 World Cup, where he helped his country reach the Round of 16. Manolas, who has two years remaining on his contract with the Greek champions, is valued at around £5 million. While that fee would be reasonable for a young player with 13 caps for his country, it could be a serious issue persuading him to move to the Emirates and except a role, at least initially, as a backup.

That could also be a major stumbling block to Arsenal’s reported interest in Schalke captain Benedikt Höwedes. The 26-year-old is naturally a center-back, although was deployed at left-back during Germany’s run to the World Cup title in Brazil, and the Daily Telegraph believes that he is one of the options being considered by Wenger. Yet, it is hard to envisage Höwedes turning his back on a key role with a Champions League side for the role of a squad player with Arsenal, however.

Instead, it could be that Arsenal turn their attention toward a player who can fill the void for a commanding presence in the holding midfield role, while also having the versatility to drop back into the center of defense. According to the Telegraph, both Luiz Gustavo and William Carvalho are under consideration to fill that requirement.

Wenger is a known fan of Gustavo, having tried to bring him in last summer from Bayern Munich before losing out to Wolfsburg. A key figure for Brazil, the 27-year-old has proved himself proficient at breaking up opposition attacks and has also operated at both left-back and center-back during his time with Hoffenheim.

Carvalho is seen as one of Europe’s best young midfielders and the 22-year-old went to the World Cup with Portugal this summer. However, the former Manchester United target will surely prove out of Arsenal’s price range, with Sporting Lisbon believed to want any suitor to match his release clause of around £35 million.

For much of the summer transfer window, there have been strong rumors suggesting that Real Madrid’s Sami Khedira was Wenger’s first choice to add some physicality to the center of his midfield. The German World Cup winner’s future with the European champions looks precarious after the arrival of compatriot Toni Kroos. Yet after a transfer for around £25 million to the Emirates reportedly broke down when Arsenal balked at the player’s wage demands, Bayern Munich are thought to be keen to secure him when his contract expires next summer. Khedira is in Real Madrid’s squad for the UEFA Super Cup against Sevilla in Cardiff on Tuesday, with manager Carlo Ancelotti refusing to divulge any further details on his future.

“Sami is a Madrid player and he has a contract until June 30 2015,” he said, according to Spanish publication AS. “There is nothing else to add. For now they are Madrid players, both Ángel [di María] and Sami.”