Occasionally, Alexandr Dolgopolov still thinks about tennis. But not very often.

The 2011 Australian Open quarter-finalist is one of thousands of Ukrainians fighting on the frontline to defend his nation in the war with Russia.

Dolgopolov, 35, joined up when Russia invaded its eastern European neighbours in March 2022, and was provided with military training to teach him how to use weapons.

He has feared for his life under Russian attack, and has seen colleagues seriously injured or killed. His days on the ATP Tour seem a long way away.

"It has been tough on the battlefield in the last year," Dolgopolov, who last played professionally in 2018 before retiring three years later because of a recurring wrist injury, told BBC Radio 4.

"When they are firing and getting really close, you know they know approximately where you are.

"When the round exits, you hear that and then you have the few seconds where it is flying - it is like loud whistles coming in - and then you feel the impact.

"You hope the impact is not exactly on the top of the trench.

"If it is one or more metres from you, you should be fine because you're half or one metre under the ground. if it doesn't hit the ceiling, you should be OK, but you don't know that."

Dolgopolov has been deployed with Ukraine's Directorate of Intelligence (GUR) in the Zaporizhzhia region of the country and is currently back in capital city Kyiv as he waits for his next assignment.

Asked about the attacks his unit faced, Dolgopolov said: "Mostly artillery fire and aircrafts, that's the main danger.

"The worst day was when mortars landed reasonably close to us.

"Usually it is random fire and if they see you, they shoot two, three, five times and then forget about it unless they see what they're aiming for. You try to hide and protect yourself.

"This time it got really intense and we got maybe 20 rounds fired at us. They were all close."

Dolgopolov describes how "comrades" have been lost, including a Georgian soldier in his unit a month ago. Another man lost his leg in an attack.

"We haven't had too many close people dead but many have been injured," he said.

"We hear a lot about other guys from other units, and friends of friends, dying.

"The longer it goes, the more people are dead."

'Is the world doing enough? I don't think so'

With the war nearing the two-year mark, Ukraine continues to face challenges - in terms of financial and military aid - as it tries to repel Russian forces.

On Tuesday, Ukrainian President Volodymyr Zelensky rejected a suggestion that the nation could be starting to lose the war.

President Zelensky said Ukraine's military wants to mobilise up to 500,000 extra people to join those such as Dolgopolov who have already signed up.

But these are costly proposals and there are fears in Ukraine that operations will be scaled back because of a drop-off in foreign aid.

Olena Zelenska, Ukraine's first lady, warned in a BBC interview earlier this month that Ukrainians were in "mortal danger" of being left to die without further Western support.

Dolgopolov, who said Ukrainian troops are able to "analyse" how the war is panning out themselves through "critical thinking", agreed.

"We need armoury and instruments to win this war. At the moment, mathematically we're not in a good position," he said.

"On the battlefield, Russia have advantages in most things - more people, more armoury and more artillery rounds.

"Is the world doing enough? I don't think so. I think it is obvious by now.

"We are not getting enough, not fast enough, not enough quantity, it is a big war and we need much more.

"I think the West needs to wake up and understand it's not just Ukraine's problem. Actions have to be taken."