'Captain America' Star Chris Evans Wishes Robert Downey Jr. A Happy Birthday

Today is the birthday of the man who helped kickstart the Marvel Cinematic Universe and the Iron [...]

Today is the birthday of the man who helped kickstart the Marvel Cinematic Universe and the Iron Man star is being celebrated by fans and costars alike -- including Chris Evans.

Evans, who plays Steve Rogers/Captain America in the MCU and was -- up until Civil War -- Tony Stark/Iron Man's best friend, took to social media to wish Downey Jr. a happy birthday. Evans even paid the Iron Man actor a compliment with the greeting.

"Happy birthday to the one and only, @RobertDowneyJr!! (Am I the only one who thinks he's aging in reverse?) I miss you, buddy!!" Evans wrote in his post.

Evans' birthday wishes joins Gwyneth Paltrow's Instagram post earlier today in which the Pepper Potts actor shared wishes from herself and some "other guy" in a photo that featured herself with Downey Jr. (The "other guy" being Spider-Man actor Tom Holland.)

Evans closes his birthday message for Downey Jr. by telling his "buddy" that he misses him and it's a sentiment that might mirror the situation between Steve and Tony in Avengers: Infinity War. When fans last saw the two in Captain America: Civil War, their friendship came undone when Tony learned that Steve knew Bucky Barnes (Sebastian Shaw) had killed Tony's parents and kept that information from him. For Tony, it's a huge betrayal but even though their friendship appeared to be over, Steve left Tony with a cell phone that Tony could use to call, just in case. It's a gesture that alludes to a chance the pair could mend fences, though Downey Jr. recently told Empire Magazine whether Tony could ever bring himself to use that phone is a significant question.

"To me the big question is could he ever in clear conscience pick up that flip phone Cap sent him at the end of Civil War," Downey Jr. said. "That is really it. For me I think back to Obadiah and that deception. It's why [former Journey lead singer] Steve Perry never went back to Journey."

Audiences will get to see both Evans and Downey Jr. back in action -- as well as find out the status of Steve and Tony's friendship -- when Avengers: Infinity War hits theaters April 27th.

Marvel Studios' Black Panther is now playing in theaters. Avengers: Infinity War hits theaters on April 27, 2018. It is followed by Ant-Man and The Wasp on July 6, 2018. Captain Marvel hits theaters on March 8, 2019, while the fourth Avengers movie lands on May 3, 2019. The sequel to Spider-Man: Homecoming hits on July 5, 2019, and Guardians of the Galaxy Vol. 3 lands in 2020.