"I just keep track of my values. I don't understand why the grand slams don't allow us to use them and I hope they reconsider the decision," said tennis world number one Aryna Sabalenka after her quarter-final win over Iva Jović.
Heart rate monitors are allowed on both the ATP and WTA tours, with the exception of the grand slam tournaments.
Sabalenka was asked not to wear a heart rate monitor before her first match at the Australian Open last week.
Previously, men's world number two Jannik Sinner has also expressed criticism of the ban.
The Australian Open says in a statement that it is "in discussions" about players being able to wear heart rate monitors in the future.
What do you think?