20th Century Fox’s 3-D event film “Avatar” led the box office with a studio-estimated $75-million take in the U.S. and Canada.

Its minuscule drop of just 3% from last weekend’s opening is a sign of extremely strong word of mouth and is continuing to fuel industry buzz that it could end up as one of the highest-grossing movies of all time, alongside “Avatar” director James Cameron’s “Titanic.” That would easily justify the massive $430 million that Fox and its financing partners invested in production and marketing.

“Avatar” has grossed $212.3 million domestically in just 10 days. As with other pictures, international grosses weren’t available yet early this morning.

The new adaptation of “Sherlock Holmes” starring Robert Downey Jr. was also a hit this weekend, opening to a very strong $65.4 million domestically. Warner Bros. and Village Roadshow Entertainment spent $90 million to produce the movie after the benefit of British tax credits, putting them in a very good financial starting position.

Fox’s family film “Alvin and the Chipmunks: The Squeakquel,” meanwhile, grossed $50.2 million for the weekend. With healthy ticket sales on its first two days in theaters, Wednesday and Thursday, it has grossed a total of $77.1 million in five days. Fox and New Regency Entertainment spent $70 million to produce the follow-up to 2007′s original big-screen version of the singing rodents and appear to have another hit on their hands.

The top three movies were drawing audiences of all ages, particularly families going out together for the holiday. Two other films aimed primarily at adults also did well, although one other movie missed the mark.

The weekend’s single disappointment was “Nine.” The Broadway musical adaptation from Weinstein Co. opened to a weak $5.5 million, bringing its total since last Friday to $5.9 million. Unless it picks up momentum from awards and audience buzz, it could be a major money loser for the struggling Weinstein Co. and its financing partner Relativity Media. Together they spent about $64 million to make the movie, which stars Daniel Day-Lewis and Nicole Kidman.