Kevin Costner is mourning his “Dances With Wolves” co-star Graham Greene.

Costner, 70, posted an emotional Instagram tribute Tuesday to Greene, who died Monday at age 73, with a clip of their characters interacting in a scene from the 1990 Western film.

“A few things come to mind when I think of Graham Greene and our time together on ‘Dances With Wolves,’” Costner began in his caption.

“I think of how willing he was to learn the Lakota language,” the “Yellowstone” star said. “I think of my joy when I heard that his work on the film was recognized with an @theacademy Awards nomination. And I think of this scene in particular, when he was able to establish so much about the relationship between Dunbar and the natives with so few words.”

Costner called Greene “a master at work and a wonderful human being.”

“I’m grateful to have been witness to this part of his lasting legacy,” Costner added. “Rest in peace, Graham.”

“Dances With Wolves,” which marked Costner’s feature directorial debut, follows a Civil War soldier (Costner) who creates a bond with a band of Lakota Indians including Kicking Bird (Greene).

The film was nominated for 12 Oscars, including Best Supporting Actor for Greene. It won Best Picture and Best Director.

Greene passed away in a Toronto hospital with his wife, Hilary Blackmore, by his side, his rep confirmed this week.

The rep said Greene lost his battle with a “lengthy illness” but did not elaborate on the exact cause of death.

Greene made his on-screen debut in 1979, starring in the Canadian drama series “The Great Detective.” His first feature film was 1983’s “Running Brave,” with his big break coming years later in “Dances With Wolves.”

The Canadian actor also starred in “Thunderheart,” “Maverick,” “Transamerica,” “Winter’s Tale” and “Wind River.” Greene’s recent TV roles included “Goliath,” “Reservation Dogs,” “1883,” “The Last Of Us” and “Echo.”

Greene claimed in 2017 that acting was something he just happened to “stumble into.”

“I started out as a carpenter, a welder, a draftsman, a carpet layer, a roadie and an audio tech,” he told Reader’s Digest Canada at the time.

“I stumbled into acting and I thought, ‘These people keep me in the shade, give me food and water, take me over to where I say what I’m supposed to say, then they take me back. Wow—this is the life of a dog,’” he added.