2018 Grand Slam Tennis: 4 things we have learnt 

#2 The younger generation are struggling to succeed

No major wins yet for Zverev

Yet again in 2018, the next generation in men's tennis finished the 2018 Grand Slam season empty-handed.

Especially for the promising 21-year-old Alexander Zverev.

The world number five struggled to get past the third round at the Australian Open, Wimbledon and the US Open.

His best was reaching the quarter-finals at the French Open.

2018 will go down as another men's tennis season where the youth have performed at ATP tournaments but just not in the four majors.

When Juan Martin Del Potro turns 30 on September 23, all current Grand Slam champions will be either 30 or older.

At some point the likes of Federer, Nadal, and Djokovic will say goodbye to the sport which will mean the future stars will have to step up.

They have a lot to do next year to change it all around.