Somewhere between Spider-Man and the Hulk, you might just find Robert Downey Jr. in a can.

Box-office expectations were big—but not crazy big—for Iron Man, which kicks off the summer movie season tomorrow (or tonight at 8 p.m., if you want to be technical about it, and include the so-called "sneak" screenings).

"This is definitely no Spider-Man 3," says Jeff Bock, a box-office analyst for Exhibitor Relations Co. "But this is a huge comic-book property."

Bock's guess: Between $80 million and $100 million, and eventual status as the second biggest comic-book movie of the summer after the latest Batman adventure, The Dark Knight.

Paul Dergarabedian, president of the box-office tracking firm Media by Numbers, pegged a $75 million-$85 million opening—or, as he put it: "Higher than X-Men but less than Spider-Man."

"We don't have a lot to go on," Dergarabedian said. "This isn't a franchise yet."

Spider-Man 3, which was the latest chapter of its franchise, jump-started last summer with a phenomenal $151.1 million opening weekend.

But as 2003's Hulk reminds, it's not always about how you start. In the case of that critically panned comic-book movie, a $62 million opening gave way to a sputtering $132.2 million finish.

In the case of Iron Man, which stars Downey as a playboy genius-turned-armored crimefighter, Dergarabedian said a debut of $50 million or less would be disappointing, but not necessarily fatal.

"Because it's good, it's going to have legs," said Dergarabedian, who caught a screening a few weeks ago.

Rob M. Worley, founder of Comics2Film.com, agreed.

"I rank it among the better superhero movies," said Worley, who watched it Tuesday night. "It's the cool, hipster superhero movie."

At one point this afternoon, Rotten Tomatoes had tracked 31 early-bird reviews, and deigned all but two of them positive. Iron Man's "T-meter" reading stood at 93 percent.

According to Worley, fan interest was nearly as hot, thanks in part to the efforts of the movie's director.

"Jon Favreau has done such a good job hyping the movie for two years," Worley said.

With good reviews and good vibes, there might just be one thing standing in the way of Iron Man and a killer weekend: Himself.

Said Worley, "He doesn't have much of a TV Q outside of comic fandom."

In other words, he's not Spider-Man, Superman or Batman.

At least not until he hits screens tomorrow night.

Here's a look at some other opening-weekend performances for comic-book movies, per the stats at Box Office Mojo:

• Spider-Man (2002), $114.8 million
• Fantastic Four (2005), $56.1 million
• X-Men (2000), $54.5 million
• Superman Returns (2006), $52.5 million
• Batman Begins (2005), $48.7 million
• Ghost Rider (2007), $45.4 million
• Daredevil (2003), $40.3 million