It’s time for one of my toughest opponents to step into my corner. Welcome aboard, coach Andy Murray,” the 24-time men’s Grand Slam singles champ posted on social media Saturday.

BBC tennis correspondent Russell Fuller assesses what Novak Djokovic's shock appointment of Andy Murray as coach could mean for both men.

The recently retired Andy Murray is going to team up with longtime rival Novak Djokovic as his coach, they both announced Saturday, with plans to prepare for — and work together through — the Australian Open in January.