Alien: Covenant, director Ridley Scott's follow-up to 2012's Prometheus, only narrowly beat out Guardians of the Galaxy Vol. 2 for the top spot this weekend at the North American box office.

REVIEW: Alien: Covenant Isn't What Fans Expect, But We Aren't Mad At It

Estimates originally pegged the Alien prequel to open anywhere from $35 million to $40 million, with Guardians of the Galaxy Vol. 2 expected to finish at about $30 million in its third weekend. However, the race ended up far closer than expected, with Covenant pulling in just $36 million, while Guardians added another $35 million to its tally.

That should be worrying for Scott, who's said he has plans for two sequels to Alien: Covenant, as the $36 million opening is down a steep $15 million from Prometheus. While the latest film was produced for a much smaller budget -- $97 million compared to Prometheus' $130 million -- the drop from Friday to Saturday could be be troublesome for the film as it tries to prove it has legs over the coming weeks.

GUARDIANS VOL. 2 took in another $63M worldwide this weekend, $732M total.

— Exhibitor Relations (@ERCboxoffice) May 21, 2017

Guardians of the Galaxy Vol. 2 has crossed $300 million domestically, and hit $732 million worldwide. The 2014 original earned $333 million in its entire domestic run, a figure Vol. 2 should pass within the next week.

In theaters now, Alien: Covenant stars Michael Fassbender, Katherine Waterston, Billy Crudup, Danny McBride, Demián Bichir, Carmen Ejogo, Amy Seimetz, Jussie Smollett, Callie Hernandez, Nathaniel Dean, Alexander England and Benjamin Rigby.