Her on-court accomplishments have long inspired, but now Serena Williams is also finding herself feted as a role model for her off-court championing of the challenges of new motherhood.

The 23-time grand slam singles champion publicly shared details of her own emotional rollercoaster journey with a clear message to others that it is OK to feel “rough” and conflicted after having a baby.

Williams, 36, who suffered life-threatening complications immediately after giving birth to daughter Alexis Olympia in September, withdrew from this week’s Rogers Cup in Canada citing “personal reasons”. Days earlier, she suffered the heaviest defeat of her career at the Silicon Valley Classic event, losing in the first round to Brit Johanna Konta, 6-1, 6-0.

In an Instagram post to her 9 million followers, Williams, who lost the Wimbledon final last month to Germany’s Angelique Kerber, revealed the difficulty she was having in attempting to balance being an athlete and mother.

“Last week was not easy for me. Not only was I accepting some tough personal stuff, but I just was in a funk. Mostly, I felt like I was not a good mom,” she wrote. “I read several articles that said postpartum emotions can last up to three years if not dealt with.

“I like communication best. Talking things through with my mom, my sisters, my friends let me know that my feelings are totally normal.

“It’s totally normal to feel like I’m not doing enough for my baby. We have all been there. I work a lot, I train, and I’m trying to be the best athlete that I can be. However, that means although I have been with her every day of her life, I’m not around as much as I would like to be.”

“Most of you moms deal with the same thing. Whether stay-at-home or working, finding that balance with kids is a true art. You are the true heroes. I’m here to say: if you are having a rough day or week – it’s ok–I am, too!!! There’s always tomm!”

The post has received more than 390,000 likes and more than 8,000 comments.

Williams has been open about the difficulties she faces balancing career and motherhood, and of her struggles with post-partum emotions.

In February she revealed the trauma she suffered after giving birth to Olympia when doctors discovered an embolism following an emergency caesarean section, which led to surgery and the further discovery of a large life-threatening haematoma in her abdomen, she wrote in an article for CNN.

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Speaking of the psychological struggle she has faced, she revealed in Harper’s Bazaar UK in May that she once cried because she could not find her baby’s bottle. “Honestly, sometimes I think I still have to deal with it. I think people have to talk about it more because its almost like the fourth trimester, it’s part of the pregnancy,” she told the magazine.

Describing the low points, Williams, who is married to the Reddit co-founder Alexis Ohanian, told Vogue magazine in January: “Sometimes I get really down and feel like, man, I can’t do this. No one talks about the low moments – the pressure you feel, the incredible letdown every time you hear the baby cry. I’ve broken down I don’t know how many times. Or I’ll get angry about the crying, then sad about being angry, then guilty, like, ‘why do I feel so sad when I have a beautiful baby?’ The emotions are insane.”

But at a pre-Wimbledon press conference, she revealed that parenthood had also been a boost to her competitive instinct. “I feel like it’s stronger because I’ve been through so much. I put so much on the back burner. I feel like even more so, I’m even more competitive…… definitely surprises me a little because I thought, you know, it would be different.

“I thought, you know, ‘Hey, I have this amazing child, I have all these grand slams, this is all super bonus,’ and it is. I definitely feel a lot less pressure out there, but I am a little bit shocked at how much I almost want that pressure. You know, I almost want to feel the need to go out there and be the best that I can be.”