Martina Navratilova has told Iga Swiatek to 'just suck it up' after the Polish player said her 'tank of fuel' was 'pretty empty' ahead of the US Open.

World No. 1 Swiatek has mentioned feeling fatigued on multiple occasions during the North American swing this summer. The 22-year-old supported other players in calling out the WTA's difficult scheduling at the Canadian Open, as rain delays saw matches be postponed until late in the evening or meant that players had to endure two matches on the same day.

After a similar situation at the Cincinnati Open the next week, Swiatek said she was 'happy' to have a longer amount of time to rest after losing to eventual champion Coco Gauff in the semi-final.

However, Navratilova, who has 18 Grand Slam titles in singles, along with 31 women's doubles titles and 10 Grand Slam titles in mixed doubles, has responded to Swiatek's comments by telling her to 'suck it up.'

"I’ve played usually two to three events between Wimbledon and the US Open," she said, "I would be tired after the US Open but not before the US Open."

"The stress on the players, I understand that – and Iga being Polish she had to play Warsaw. Normally, if she wasn’t Polish, she would have never played [that event] and would have taken an extra couple of weeks of rest so maybe that’s why she’s tired.

"But I still have to say, ‘Come on, just suck it up’. It’s September, you didn’t play that many tournaments and this is the US Open. So if you can’t get up for that… if you’re that mentally tired, don’t play.

"Take the time off and concentrate on the season-ending tournament. Just take the time off. Force yourself to take the vacation. That’s okay. I never gave myself permission to do that, never occurred to me that I could do that.

"Or just get on with it and say, ‘Okay, I’m fine. It’s just two weeks, it’s seven matches, I literally have to work hard [for] maybe 20 hours, these next two weeks.’

"So put it in perspective, take the pressure off yourself and say, ‘Okay, I’m just gonna give everything I have when I play the matches.’ The rest of it is stress-free, everything’s done for you. You just have to show up, practise for an hour, all the physical work has been done.

"You just suck it up and say, ‘Okay, get on with it’ and put it in perspective to what normal people do for a living. Yeah, you’re in the spotlight but you know, nice problem, right?

"This is what you want all your life and here you are. So you just gotta toughen up on that front. I don’t have that much sympathy for that when I think about what we went through. Get on with it," she added.