7 youngsters who impressed the most during the 2018 tennis season

5. Kyle Edmund

Just like Chung, Edmund also sparkled during the Australian Open and reached the semifinal, defeating Grigor Dimitrov in the process.

He won his first ATP title in Antwerp, and became Britain's new hope in the absence of Andy Murray this year.

Ranking at the start of the year: 50

Ranking at the end of the year: 14

Career-best ranking: 14 (October 2018)

Win-loss index in 2018: 36-21

4. Daniil Medvedev

The tall and skinny Russian won three ATP titles this year, including one in Tokyo. With his big serve and aggressive play, he climbed up the rankings steadily through the year.

Medvedev is a potential Top 10 player, without a doubt. He won the Tokyo title despite entering the tournament as a qualifier, and he didn't drop a single set in the main draw.

Ranking at the start of the year: 65

Ranking at the end of the year: 16

Career-best ranking: 16 (November 2018)

Win-loss index in 2018: 43-24

3. Borna Coric

Croatia's Borna Coric had a dream season in 2018. He broke into the Top 20 this year and to top it all he defeated Roger Federer twice - including once on grass.

Coric also had a terrific run in Shanghai, losing only to Djokovic in the final.

But it's not just about his achievements; the Croat's game has improved a lot this year. He is serving well, his forehand has become more penetrating, and he finished the year by helping Croatia win only their second Davis Cup title.

Ranking at the start of the year: 48

Ranking at the end of the year: 12

Career-best ranking: 14 (November 2018)

Win-loss index in 2018: 40-20