Isco has accepted after receiving many approaches from different countries — done as called by @Plettigoal.
Fabrizio Romano tweeted: "Union Berlin are set to sign Isco on free transfer, here we go! Agreement now in place and medical tests scheduled on deadline day. Huge one for Union."
The 30-year-old has been available since the end of 2022 following a controversial departure from Sevilla in December.
Jorge Sampaoli ruthlessly dropped Isco from his plans, despite the experienced star only joining the club last summer, with the Argentinian criticising his lack of effort at the Estadio Ramon Sanchez Pizjuan.