Del Potro posts tribute to his departed dog

When a dear pup passes, it's proper to go into mourning for as long as one needs. Juan Martin del Potro did so on social media in the wake of his own best friend, a Newfoundland named Cesar.

"I'll miss you a lot, faithful companion," he wrote on Instagram. "You accompanied me in these almost 10 years, you waited for me with joy after each trip, you protected me, you made happy a whole family and today you go to rest in peace leaving your mark on my heart. Goodbye, Cesar."

Newfoundlands such as Cesar can grow as heavy as 150 pounds and typically live to 8 to 10 years of age.

Del Potro was always fond of returning from so many tournaments over oceans to his best friend.

"I missed you!" he wrote in another post, that from mid-December 2016 as he lounged in a pool with Cesar.

The 29-year-old, forever a dog lover, is presently perched at No. 10 in the ATP World Tour rankings.

Just as Delpo pursues another major singles title, may he yet again experience the unabashed love of a dog. That time will come.

Follow Jon on Twitter @jonscott9.