Deadline reports the movie's headed for a $15.2 million opening ... nearly doubling the next highest opening -- that movie's called "Unsung Hero," and the trade publication says is headed for an $8 million weekend.

The outlet's telling "Challengers" producers to hold their horses though ... 'cause $15 million's pretty far from the reported $50+M budget this flick carries.

And, in case you're wondering ... Deadline says PostTrak -- a data company that talks to movie audiences as they leave the theater -- confirmed people are coming out to see Zendaya. They say 55% of respondents came because of her.

But, whether those audiences enjoyed the flick ... kinda unclear at this point. According to Rotten Tomatoes, 88% of critics enjoyed the movie -- much higher than the 77% of audience members who said the same.

77% is still pretty high ... but -- with a movie this anticipated -- 1 in every 4 reviewers bombing the flick doesn't exactly bode well for attracting future audiences.

Of course, many know the movie from the sexual tension in the trailer ... including a scene where two men kiss Zendaya's neck. It's been on people's calendars for a while now because of it -- and, perhaps early audiences built the flick up too much in their heads.