Mikel Arteta made a special request to the Arsenal board to sign Willian, according to reports.
The Brazilian underwent a medical in north London on Monday ahead of signing for the club as a free agent.
And the Mirror says Arteta pleaded with the board to sign Willian, despite his age of 32.
He believes Willian will significantly improve his squad after seven successful years at Stamford Bridge.
The Gunners offered him a three-year deal, one year more than his former club Chelsea.
He will reportedly earn around £150,000-a-week at the Emirates.
