How Ferrero gels with Shelton’s dad – a former professional player who won two ATP titles – will be key.

Ferrero previously had a six-month spell coaching Zverev, which ended after a third-round Australian Open exit in 2018.

Ferrero was hired by Zverev as an outside voice coming into a father-son coaching dynamic, but the German fired him after claiming Ferrero was “disrespectful” to his team.

Ferrero later said Zverev lacked the professionalism he expected from a top player.

Shelton, known for having a strong work ethic and insatiable will-to-win, is likely to be receptive to Ferrero’s demands – as long as they do not neutralise his raw weapons.

But Rick Macci, the veteran American coach who guided the Williams sisters as teenagers, believes Ferrero will find it harder to improve Shelton’s technical deficiencies.

“Shelton can win a few Slams if things break his way,” Macci said.

“His backhand groundstroke and return can be technically unpredictable – at the top of the mountain the margins are razor thin.

“Ferrero can help a lot in many areas because [Shelton’s] backbone is better than his backhand, but getting to number one is a different landscape to mow.”