After one of the biggest upsets at this year's Oscars, Sylvester Stallone shared an inspirational message on Instagram on Monday and thanked his fans for their support.

Stallone was considered the front-runner to win the Oscar for Best Supporting Actor for his performance in "Creed." The 69-year-old already has a Golden Globe and Critics' Choice Award under his belt for his role as Michael B. Jordan's mentor in the "Rocky"-inspired film. However, the actor was left empty-handed on Sunday, losing out to Mark Rylance, who bagged the award for "Bridge of Spies."

The other actors nominated in the category included Christian Bale ("The Big Short"), Tom Hardy ("The Revenant") and Mark Ruffalo ("Spotlight").

Stallone's Oscar nomination was his first in almost four decades after being nominated in the Best Actor category for the original "Rocky" film in 1977. He also picked up an Oscar nomination in the Best Writing category for the film.

"To all the 'real Rocky's' of the world, Please hang on to your dreams, NEVER GIVE IN, NEVER GIVE OUT, NEVER GIVE UP! thanks for the support," Stallone captioned a picture of himself.

After Stallone's Oscar snub, his brother, Frank Stallone, rushed to his defence and went on a nasty Twitter rant. "The Academy should be ashamed of themselves," he wrote. "It's as clear as the nose on your face that Sly won. Mark who? It's total Hollywood bulls--t."

"Mark Rylance couldn't even comb his hair for Christ sake this is the 3rd time Sly's gotten ripped off Rocky, Copland and Creed. New Voters," he added.

Frank later apologized for his remarks on Rylance but said that he still thinks his brother should've won. "I will always defend what right but I was wrong to put down Mark Rylance and I apologize. He is a fine actor but I thought Sly deserved it," he said.

Stallone also apologized for Frank's actions on Instagram by sharing another picture of himself captioned, "Sorry, didn't mean for this picture to go up before saying that I'm very happy and please understand my brother is so em motional because he is just very protective and only wants the best for me. Life is good!"