'Ted Lasso' Star Brett Goldstein Has 'Best Day' of His Life Meeting Oscar the Grouch on 'Sesame Street'

Goldstein, who plays a bit of a grouch on the beloved TV series, detailed meeting his 'Sesame Street' counterpart.

It was the ultimate meeting of the grouchiest of grouches on Sesame Street Tuesday.

Ted Lasso star Brett Goldstein just guest starred on the iconic children's program, in what he called "the best day" of his life.

Goldstein, who plays the always-grouchy Roy Kent on the Apple TV+ series, took to Instagram to share snaps from the epic day, which included a cameo with his Sesame Street counterpart, Oscar the Grouch, Cookie Monster, Big Bird and more.

"Brett, how would you show the best day of your life using only photos…," he wrote, kicking off his tribute to the long-running television series.

"I finally found my way to Sesame Street (all you have to do is ask, through the medium of song) and it was more wonderful than I could have imagined. Everyone was so funny and brilliant and friendly and kind. I managed to get to say hi to all the residents except Snuffleupagus who was sleeping (although I saw him sleeping and he snores less than you’d think.)," he continued.

Goldstein went on to thank Sesame Street's cast and crew before teasing that fans can catch his episode of the PBS series later this year.

"Truly a beautiful cast and crew that fill that whole street with all the love you could wish for. Special thanks to Elmo and Grover and Big Bird and Oscar and Cookie Monster, sorry if I scared you. Extra special thanks to @karynl5, @sherrierwestin, Stephen M Youngwood and Zack Van Amburg for making this dream come true. It was perfect," Goldstein said. "Full episode later this year on @sesamestreet."

Sesame Street teased a clip from the episode on Twitter. In the 16-second spot, Goldstein and Oscar are in their respective receptacles when a cheerful Big Bird walks by.

Unimpressed by the big yellow bird's excitement for the day, the pair slowly slither back into their cans and close the lid.

"Grouches gonna grouch on Sesame Street. 💚 Thanks for visiting our neighborhood @BrettGoldstein! We love you!" the show's Twitter account captioned the clip.

ET recently spoke to Goldstein's Ted Lasso co-star, Hannah Waddingham, who is gearing up to head back to Richmond as season 3 of the beloved series begins production.

"They are just brilliant, brilliant brains, but they know better than to tell me anything at all," said the actress, who plays AFC Richmond team owner Rebecca Welton.

Waddingham confirmed to ET that after some delays, the show is due to start production on season 3 in early March. Much ado has been made about the series' planned three-season run, which would make the upcoming episodes their last, but, given that the show has been such a hit with fans and critics alike, many, Waddingham included, can't help but wonder if Jason Sudeikis might end up changing his mind.

"He has always said that there is a beginning, a middle and an end," she recalled, "which is why he was very specific about telling everyone that [season 2] was the middle, Empire Strikes Back kind of vibe."

However, Waddingham admitted, "If I were Apple and Warner Bros., I'd be leaning on him like a lunatic and putting him in a corner in a little cage and giving him a notebook and a pen... It's too beautiful."

For more on Ted Lasso, watch the video below.