The two words were written on the pink visor she wore against Collins who secured a 6-1, 6-4 victory at the Hard Rock Stadium in the American city.

Zvonareva, a women's singles bronze medallist at the Beijing 2008 Olympics, is playing as a neutral along with other Russian and Belarusian players after tennis authorities barred them from competing under their nation’s name and flag in response to the war on Ukraine.

The 37-year-old former world number two is also not the first tennis player to speak out against what Russian President Vladimir Putin is describing as a "special military operation".

Last month, her compatriot Andrey Rublev wrote "No war please" on a camera after beating Poland’s Hubert Hurkacz in the semi-finals of the Dubai Tennis Championships.

Collins’ victory over Zvonareva sees her set up a last-16 clash with Tunisia’s eighth seed Ons Jabeur, who defeated Estonia’s Kaia Kanepi 6-3, 6-0.

Japan’s Naomi Osaka progressed to the next stage without having to hit a ball after Karolína Muchová of Czech Republic was forced to withdraw from the tournament due to a left abdominal injury.

Like Osaka, Italy’s lucky loser Lucia Bronzetti moved through to the fourth round courtesy of a walkover after Russian Anna Kalinskaya pulled out because of a left arm injury.

Bronzetti will next face Australian wildcard Daria Saville who also benefitted from her opponent getting injured as Katerina Siniakova retired hurt after losing the opening seven games.

Olympic champion Belinda Bencic of Switzerland saw off Britain’s Heather Watson 6-4, 6-1, while Americans Alison Riske and Russian Aliaksandra Sasnovich won three-set matches.

Riske defeated Ann Li 6-2, 3-6, 6-2 in an all-American third-round battle, while Sasnovich overcame Irina-Camelia Begu of Romania 7-5, 6-7, 6-4.

Russian world number one Daniil Medvedev proved too strong for three-time major winner Sir Andy Murray of Britain in the men's singles second round as he powered through with a 6-4, 6-2 victory.

"I think it was a great match," said Medvedev.

"I’m happy that he managed to have zero break points against me.

"I feel like I have some room for improvement, but it was a great match against an amazing player and I’m happy that I managed to get through."

Defending champion Hurkacz got his campaign underway with a 7-6, 6-2 triumph against France’s Arthur Rinderknech.

Fresh from winning the Indian Wells Masters, 11th seed Taylor Fritz of the US showed grit and determination to beat Kazakhstan’s Mikhail Kukushkin 6-3, 5-7, 6-3.

Greek third seed Stefanos Tsitsipas was taken to three sets as he outlasted American JJ Wolf 6-4, 6-7, 6-1.

"I very much know how to handle situations like this, speaking from experience,” said Tsitsipas.

"I think letting go and relaxing a bit helped me a lot and gave me that win."

Tsitsipas will next meet Alex de Minaur who claimed a 6-2, 6-3 victory in an all-Australian tussle with Jordan Thompson.

Canada’s seventh seed Felix Auger-Aliassime was the biggest casualty in the men’s draw as he went down 6-4, 6-2 to Serbia’s Miomir Kecmanović.

Auger-Aliassime was one of a number of seeds to fall as compatriot Denis Shapovalov, Georgian Nikoloz Basilashvili, Russian Karen Khachanov, Britain’s Daniel Evans, Chile’s Christian Garin and Spain’s Albert Ramos- Viñolas also suffered second-round defeats in Miami.

Competition is due to continue tomorrow.