United Kingdom, Dec. 17 -- Sir Andy Murray broke down in tears admitting he was "really upset" by his friend Sir Chris Hoy's "cruel" cancer diagnosis.

The 48-year-old cycling champion - who has two young children with wife Sarra - revealed earlier this year that he was being treated for incurable prostate cancer and now his tennis ace pal has opened up about the shocking moment he learned of Hoy's health crisis.

Speaking to BBC Breakfast presenter Sally Nugent for documentary Sir Chris Hoy: Cancer, Courage and Me, Murray explained: "After I retired at the Olympics last year, the following day I went to the GB house and he [Hoy] interviewed me.

"I messaged him afterwards. I didn't want to ask because there was lots of people around, lik...