Ana Ivanovic said she was thrilled for men's world number one Novak Djokovic on Wednesday after her childhood friend announced the birth of his first child.
Ivanovic, who grew up playing tennis with Djokovic in war-torn Belgrade, said she had goosebumps when she heard the news about his baby son, Stefan.
"It's actually a scary thought. We're the same age," the 26-year-old told reporters at the WTA Finals in Singapore, where she beat Eugenie Bouchard 6-1, 6-3 on Wednesday.
"But it's great news. I actually found out this morning after I woke up, and I was really thrilled for them. It's one of the best moments you can have in life, you know.
"I got goosebumps. It's really thrilling, and I'm really happy for them."