NEW YORK — “Eternals,” one of Marvel’s most ambitious efforts to expand its superhero universe, arrived in theaters with about $71 million in ticket sales over the weekend, according to studio estimates.

By most studios’ box-office standards, the opening was enviable. Only three other films have debuted better during the pandemic: “Black Widow” ($80.3 million), “Shang-Chi and the Legend of the Ten Rings” ($75.3 million) and “Venom: Let There Be Carnage” ($90 million). But for Marvel’s well-oiled blockbuster machine, the “Eternals” launch in some ways constituted a bump in the road in an 26-film streak.

Forecasts had been only slightly higher at about $75 million domestically. More concerning for the Walt Disney Co. was the mixed audience response to Chloé Zhao’s movie about an immortal race of superheroes. The film is the first in the Marvel “cinematic universe” to rank “rotten” in Rotten Tomatoes’ aggregate critic score, with only 47% of reviews considered positive.