Lupita Nyong'o has written a touching tribute to her friend and Black Panther (2018) co-star Chadwick Boseman, who died at 43 of colon cancer in late August.

Breaking her silence on Boseman's death, the 37-year-old actress wrote on Instagram on Tuesday (Sept 8): "I am struggling to think and speak about my friend, Chadwick Boseman, in the past tense. It doesn't make sense."

Nyong'o, who played his love interest Nakia in the groundbreaking Marvel movie, posted a photo of Boseman laughing with her hand on his shoulder.

She said: "The news of his passing is a punch to my gut every morning. I am aware that we are all mortal, but you come across some people in life that possess an immortal energy, that seems like they have existed before, that are exactly where they are supposed to always be... Chadwick was one of those people."

The actress recalled the making of Black Panther. "I remember being struck by his quiet, powerful presence. He had no airs about him, but there was a higher frequency that he seems to operate from."

Nyong'o, whose film credits include 12 Years A Slave (2013) and Us (2019), praised Boseman for setting "the bar high by working with a generosity of spirit, creating an ego-free environment by sheer example, and he always had a warm gaze and a strong embrace to share".

She ended the post by saying: "We are all charged by his work as a result, by his presence in our lives. His power lives on and will reverberate for generations to come."

She had earlier attended a memorial for Boseman in Malibu, California, with other Black Panther co-stars Michael B. Jordan and Winston Duke.