Arsenal have signed Brazil defender Andre Santos from Fenerbahce on a "long-term contract" and are set to complete a deal for Werder Bremen centre-back Per Mertesacker, the English Premier League club announced Wednesday.
Santos's deadline day transfer came with Arsenal manager Arsene Wenger looking to bolster his defence following the Gunners' 8-2 thrashing by English champions Manchester United last weekend.
Wenger has also agreed terms with Werder for Germany international Mertesacker, who will join for a reported fee of Â£8million.
"Arsenal has confirmed they have agreed terms with Werder Bremen to sign German international defender Per Mertesacker. The deal is subject to the completion of formal registration processes," the Gunners confirmed.
Santos, 28, helped Fenerbahce win last season's Turkish title but did not feature in Brazil's 2010 World Cup squad.
He is reported to have joined the Gunners in a Â£6.2million deal as they look to plough some of the money from the lucrative transfers of Cesc Fabregas and Samir Nasri, to Barcelona and Manchester City respectively, back into rebuilding the squad.
"Santos is a quality player, with the ability to both defend well and get forward and help with attacks," Wenger told Arsenal's website on Wednesday.
"He has experience in the Champions League and for Brazil and has proven he can deliver at the highest level.
"We welcome Santos to the club and look forward to him having a big impact for us."
Santos becomes the latest Brazilian to head to Arsenal, following compatriots Denilson, Sylvinho, Edu and Gilberto Silva.
"It was one of my dreams to play for a major European football club and I have accomplished this. I am very happy to be part of this team," Santos said.
"All the Brazilians who came to this club spoke wonders about it and I am delighted to be part of the Arsenal family."
Wenger has been active in the final few days of the transfer window, signing South Korea captain Park Chu-Young from Monaco, the club where the Frenchman made his name as a manager, on Tuesday.
The Gunners have also been linked with moves for Everton duo Marouane Fellaini and Mikel Arteta along with Edin Hazard of Lille, CSKA Moscow's Japan star Keisuke Honda and Yann M'Vila at Rennes.