Coach Vladimir Platenik says his very brief partnership with Emma Raducanu ended because the Briton "was feeling stressed and under a lot of pressure".
Platenik told BBC Sport he was "absolutely surprised" but "not angry" when the 22-year-old called off the arrangement after only two weeks.
The conversation took place after 10 days of training and on the eve of the British number two's first-round match at the Miami Open on Wednesday.
"I totally understand Emma, she's not in an easy position. The world is looking at her after the US Open [which she won in 2021] and everybody is expecting - including herself - what she is going to do next," Platenik said.