Muguruza previously worked with the 1994 Wimbledon Champion during her Fed Cup days and on a trial basis between 2017 and 2018 which saw her win Wimbledon.
She went on to work with Sam Sumyk while Martinez began to work with Karolina Pliskova; who has had lots of success since then.
Both players though announced that their prior coaching relationships were ending though which ultimately gave them a window of opportunity to work together again.
It will be a task for Martinez due to Muguruza sliding down to World No.35 but with the duo knowing each other well, they will hope it's a shrewd move.
https://twitter.com/GarbiMuguruza/status/1198179295128109056