SAN DIEGO -- The lines outside the San Diego Convention Center were almost as long as the ones inside as Comic-Con guests queued up to collect freebies and collectibles during the four-day festival's preview night.

The 43rd annual Comic-Con International pop-culture convention officially begins Thursday, but those with four-day passes got a peek at the convention-centre floor Wednesday night.

Fans swarmed the massive space, filling their oversized convention tote bags with free souvenirs and limited-edition toys available only at Comic-Con.

"For nerds, Comic-Con is a total safe zone," said Chris Hardwick, TV host and founder of Nerdist.com. "A lot of times, you have to keep the stuff you're passionate about at bay, but here, it's the fun, safe zone, where you get to be as open about your loves as possible."

The first night especially: "It's like bragging rights," he said. "I've already been in; I've already seen it."

So grown men proudly played the kids' card game Yu-Gi-Oh! while others waited in long lines for free Cartoon Network posters and other cool collectibles. Booths from Disney, Warner Brothers and other major companies beckoned with bright displays, giveaways and events.

"For the hard-core people who don't want to miss out, for people who want to see the latest and greatest, tonight's the night," said Andy Gore, chief of Quantum Mechanix, which sells miniaturized models of the USS Enterprise and other downsized keepsakes from the fictional world of film.

"This is the night that everyone gets to open their Christmas presents," he said.

Some distributors sold out of their collectible offerings just an hour into the festival's preview night.

Collectors carting crates full of toys passed other passionate fans camped out on the grass near the convention centre, who hoped to be first in line for various popular presentations Thursday, including those dedicated to the final "Twilight" installment and the popular book "Fifty Shades of Grey."

Comic-Con continues through Sunday.