Serena Williams lost her dog 16-year-old Jackie on Tuesday, who had been by her side since 1999.
In memory of her longtime friend, the 21 Grand Slam champion posted an absolutely heartbreaking post on Facebook and Instagram, writing, "Today really is hard for me. My special friend which I got at 17 (2 weeks before I won my very first Grand Slam) left me today."
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"She was 16 years young and up until a few days ago was still sprinting," the 34-year-old continued. "Her poor body gave out this morning and she had a way of telling me it was time for me to be brave and let her go. With my dad by my side we were able to say a loving goodbye."
"She was with me from 1999 until today and I miss her so much. I got out of the shower this afternoon and she was not there to lick my leg as she always did everyday to remind me how much she loved me," she said. "I feel so lucky to have such a special friend. Give your dog, cat, pet a big hug. #breakingheart #bff Jackie Baila Pete Williams I will miss you and your memory will live forever."
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A followup Instagram picture that she posted simply read, "My angel."
"Lauralei, Chip, and Mommy miss you so much," the tennis pro wrote in another post. "We will never forget u."
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Jackie was with Serena throughout her prolific tennis career, and in 2000, the young pro shared her three secrets to victory. Watch the video below.