10. Spain. Anabel Medina Garrigues. Won 11 WTA Tour titles and had a highest ranking of WTA World No.16. (Getty)

Leading by example: How the Fed Cup captains fared as players

On April 15, Kristina Mladenovic announced a new partnership with Osaka’s former coach, Sascha Bajin. (Twitter)

In pictures: 2019's coaching carousel

Polona Hercog was the champion at the Samsung Open in Lugano (tournament)

Vive la difference! 18 titles, 18 winners in 2019 so far

New Bogota champion Amanda Anisimova rises 22 places, to World No.54 (Jimmie48/WTA)

Rankings Rockets: Teenagers Anisimova and Swiatek soar

Veronika Kudermetova came from a double break down in the third set to beat Jil Teichmann 6-2, 4-6, 7-6(2) in the first round of Lugano, saving two match points as the wildcard served for the match at 5-4 (Samsung Open)

Great escapes: Kudermetova, Ahn join 2019's winners from match point down

Australian Open girls' champion Clara Tauson extended her winning streak to 17 by coming through Lugano qualifying, and the 16-year-old World No.413 stretched Evgeniya Rodina all the way before losing a first-round thriller 6-7(2), 6-2, 7-5 (Getty)

Welcome to the Tour: All of 2019's WTA debutantes

Victoria Azarenka made the first final of her comeback from maternity leave in Monterrey, rising seven places to World No.60 as a result (Abierto GNP Seguros)

Rankings Rockets: Azarenka ascending, Keys back in Top 15

Irina Falconi of the USA defeated Silvia Soler Espinosa in 2016's three-set thriller, edging it 6-2, 2-6, 6-4 (tournament)

Brilliant in Bogota: From Duque Mariño to Schmiedlova

Azarenka ensured Kerber's joy was short-lived, beating the German for a seventh time in the Miami semifinals 6-2, 7-5 (Getty)

Rivalry Record: Angelique Kerber vs Victoria Azarenka

The pair hug at the net after their French Open semifinal (Getty)

Rivalry record: Madison Keys vs Sloane Stephens

Miami semifinalist Anett Kontaveit's new career high of World No.14 makes the 23-year-old the best-ranked Estonian in history, beating Kaia Kanepi's previous national record by one spot (Jimmie48/WTA)

Rankings Rockets: Kontaveit sets national record, Vondrousova vaults to new high

World No.3 Petra Kvitova won the Sydney International and was runner-up to Osaka at the Australian Open (Getty)

The WTA Top 10 and their 2019 best result: Osaka remains No.1, Barty breaks in