#4 Karolina Pliskova
Among the current roster of WTA players, no player has a better serve than Karolina Pliskova. Over the last 3 years or so, Pliskova has topped the 'Most Aces' charts on the WTA Tour. The powerful 6'1 Czech uses her dominant serve to considerable advantage and that has helped her attain the World Number 1 ranking.
Pliskova has won 11 WTA titles till date and is presently ranked 7th on the WTA Tour ranking. Her best Grand Slam performance till date was at the final of the 2016 US Open, where she finished as the runner-up. She lost a tough 3-set contest to top seed Angelique Kerber.
Pliskova has helped Czech Replublic win the Fed Cup on 3 different occasions. The year 2016 was also a momentous one for Pliskova in terms of her doubles performances as she reached a career-high ranking of World Number 11 in doubles that year.