Based on the deafening cheers that shook the walls of the Paramount Theater in Austin, Texas on Monday, the SXSW Film Festival premiere of “John Wick: Chapter 4” was a rousing success — and that’s before the film had even started. All it took was star Keanu Reeves to step on stage at the behest of director Chad Stahelski for the 1,000-plus audience to erupt in unbridled enthusiasm.

That fervor never waned throughout the film’s epic two-hour-and-49-minute runtime, with booming ovations following the prodigious action sequences in Osaka, Berlin and Paris — and vocal gasps after several major twists.

Stepping onto the stage after the screening, Reeves and Stahelski both seemed pleasantly shell-shocked by the raucous reception.

“You guys are amazing,” Reeves said. “Thanks for that experience. You guys are fucking awesome.”

Added Stahelski, “This is one of the best audiences of all time.”

Reporting on the rest of the post-screening Q&A, however, is a bit of a challenge, as the conversation at times drifted into serious spoiler territory — including Reeves’ answer for his favorite moment in the movie, which elicited a chorus of “Awwwws” from the audience.

Stahelski’s answer was, at least, spoiler-free: “It was the first day Keanu came on set,” he said. “He had the suit back on and it was the first time we were back together in three years. So it was pretty special.”

Like every other “John Wick” film, “Chapter 4” is steeped in baroquely staged and choreographed fight scenes, including one that unfolds in one unbroken take which Stahelski said took a week to film. Then Reeves cut in: “And months and months of planning and training.”

Much of the Q&A involved audience members launching into extended tributes to the film’s star. One person asked Reeves if he ever ages.

“Yeah man, I age,” he replied wearily. “I really — I age. It’s happening, man.”

After Reeves said he kept Wick’s watch and wedding ring from the previous movies, someone shouted, “I’ll marry you!”

“Yeah, be careful what you wish for,” Reeves replied.

Another person yelled “Bring back ‘Constantine’,” referencing Reeves’ beloved 2005 DC adaptation.

“I’m trying, man,” the actor said with a sigh.

One of the final questions came from someone who, appropriately, had a puppy with him, who asked if Reeves was planning to appear in the upcoming “John Wick” spin-offs, including the series “The Continental,” due to premiere on Peacock later this year, and “Ballerina” starring Ana de Armas.

Both Reeves and Stahelski seemed unsure of how to answer.

“Uh, not sure yet,” the director said, followed immediately by a tentative “No” from Reeves — who then contradicted himself. “I have a cameo in ‘Ballerina,’ that’s true.”

“John Wick: Chapter 4” will open in theaters on March 24.