It has been a year of disappointment for the former top 10 player.
Daria Kasatkina lost her seventh match of the year to Venus Williams, while Mertens, Sevastova and Collins were also knocked out.
As the second rounds approach in Indian Wells, here are five players that need a good tournament in California, which includes finalist Daria Kasatkina.
Daria Kasatkina has decided to split with her coach Philippe Dehaes in the latest WTA coaching chaos.
Kimberly Birrell stunned world number 10 Daria Kasatkina in a last set tiebreak to reach the second round of the Brisbane International.
Daria Kasatkina won her first Moscow title in emotional circumstances as she edged Ons Jabeur in a three set battle.
Daria Kasatkina overcame Britain's Johanna Konta in straight sets to reach the final in Moscow for the second consecutive year.
Maria Sharapova hammered Russian number one Daria Kasatkina 6-0 6-2 at the Rogers Cup and will next face Caroline Garcia.
Angelique Kerber will take on Jelena Ostapenko in the last four after overcoming Daria Kasatkina in a terrific quarter-final battle.
Johanna Konta was knocked out by Cibulkova, Kerber fought back from a set down to beat Claire Liu and Ostapenko thrashed Kirsten Flipkens.
Daria Kasatkina talked about her addiction to tennis, her relationship with grass and which teams she is watching at the 2018 World Cup.
Caroline Wozniacki looked to be in danger of losing to Daria Kasatkina when bad light forced play to be suspended.
Madison Keys progressed to the fourth round of the French Open for the second time by beating Naomi Osaka in straight sets.
Karolina Pliskova loses 3-6 6-3 7-5 to Maria Sakkari in a huge upset in the second round of the Italian Open, while Halep thrashes Osaka.
MADRID: Russian world No.15 Daria Kasatkina resisted some big hitting from Garbine Muguruza to progress into the third round of the Madrid Open. Taking on the...
Julia Goerges produced an excellent display to end the run of defending champion Daria Kasatkina and book her place in the Charleston semi-finals for the first...
Madison Keys reached her third quarter-final in Charleston by beating Camila Giorgi 6-4 6-3, while Daria Kasatkina and Julia Goerges beat Irina-Camelia Begu and Naomi Osaka...
Defending champion Daria Kasatkina overcame a massive scare to defeat Christina McHale 6-3 3-6 6-2 and earn a place in the third round in Charleston.
Johanna Konta got her Miami Open title defence off to a good start with a comfortable 6-4 6-3 win over Kirsten Flipkens. The Brit lost 11...
Naomi Osaka claimed her first WTA title after producing a commanding display to beat Daria Kasatkina 6-3 6-2 in the BNP Paribas Open final in Indian Wells. The...