Pakistan, Aug. 22 -- Hayden Panettiere would have turned 37 years old on Friday. Marking the special occasion on Friday, August 21, her ex-fiance Wladimir Klitschko - who is also the father of her only child - took to Instagram with a bittersweet tribute.

"Today is Hayden's birthday. Instead of celebrating the way we had planned, today we celebrate her life, her spirit and the love she brought into this world," the Ukrainian former boxer wrote alongside a radiant picture of the late Heroes star.

Klitschko went on to thank fans for "the outpouring of love and support," adding, "At a time filled with so much sadness, your kindness has reminded me that there is still so much good in humanity."

The birthday tribute ended with a request to ...