Arsenal have completed the signing of Per Mertesacker's transfer from Werder Bremen, and have also sensationally resurrected their collapsed move for Mikel Arteta.
The Germany defender signed what the club described as "a long-term contract" for an undisclosed fee, believed to be around £8million.
Mertesacker said: "I had a great time at SV Werder Bremen and I'm grateful to the club."
He added: "Moving to London enables me to fulfil a dream and a further step in my career.
"The Premier League has always represented a great challenge for me."
Manager Arsene Wenger told his club's official website, www.arsenal.com: "We are delighted to welcome Per Mertesacker to the club.
"He is a German international with vast experience and strength and is good on the floor and in the air.
"I believe he will be well-suited to the Premier League and a tremendous asset to the team."
Meanwhile, the Arteta deal was thought to be dead after the Gunners had a bid rejected on Wednesday afternoon, with reports suggesting Everton had turned down a part-exchange offer.
But it it appears Arsenal may have bowed to the Toffees' demand for a cash-only offer, meaning they faced a race against time to get everything wrapped up before the 11pm deadline.