World number one Iga Swiatek has criticised the upcoming scheduling of tennis events, saying she will not be able to compete at next month's Billie Jean King Cup Finals.
The world number one had planned to represent Poland in the finals, which begin in Glasgow on 8 November.
However, the WTA Finals in Texas are due to end the day before.
The three-time Grand Slam champion said the schedule "is not safe", adding she felt "sad" to miss an event.
"I was thinking it through a lot and discussing it with my team, but I will not be able to play at the Billie Jean King Cup in Glasgow," Swiatek announced in a post on Instagram.
"It makes me sad. I'm very sorry, because I play for Poland whenever it's possible and I always give it my best.
"Playing in Poland this year [in the qualifiers] was an honour and I hoped to do this again at the end of the season."
The 21-year-old won her first US Open title last month - her second major win in 2022 after triumphing at the French Open for a second time.
Swiatek will contest the season-ending WTA Finals from 31 October in Fort Worth, Texas, which sees the top eight players on the Race to the WTA Finals compete in a round-robin format.
Players would have one day to travel from Fort Worth, which is six hours behind Glasgow, to make the Billie Jean King Cup Finals and represent their country.
"I'm disappointed that tennis governing bodies didn't come to an agreement on something as basic as the calendar of tournaments, giving us only one day to travel through the globe and changing the time zone," Swiatek said.
"The situation is not safe for our health and could cause injury.
"I'm going to talk to the WTA and ITF in order to change something. This situation is difficult not only for the players like me, but mainly for the tennis fans that support our sport."