Recently-retired Radek Stepanek is joining Novak Djokovic's coaching team.
The former world number one will continue to work with Andre Agassi at the grand slams and possibly other big tournaments but has been without a touring coach since splitting from long-time mentor Marian Vajda in May.
Czech Stepanek, 39, called time on his playing career earlier in November after struggling to recover following back surgery.
He reached a career high of number eight in the world in singles in 2006 and won two grand slam doubles titles and two Davis Cups.
The pair announced the new arrangement in a live post on Instagram, where they pretended to talk about the possibility of Stepanek coaching Djokovic before the Serbian opened a door to reveal the new member of his team.
Djokovic said: "This is the new team, this is my new man. We are excited for the new season."
Although Stepanek's playing career does not compare to Djokovic or Agassi's, the Czech is considered to have one of the sharper tennis brains around.
A quirky character with a game to match, he also stood out on the court for his individual fashion sense.
Stepanek's first task will be to help Djokovic work his way back to full match sharpness.
The 30-year-old has not played a match since Wimbledon, after which he announced he would be taking the rest of the season off to allow an elbow problem that had dogged him for months to heal.
Djokovic is due to return to action in Doha at the QatarExxonMobil Open, which begins on January 2.