More than 10 million people tuned in to see the special 50th anniversary episode of Doctor Who in the UK, according to overnight viewing figures.
At its peak, the show was watched by 10.61 million viewers, with an average of 10.2 million across the 75-minute running time.
It comfortably beat X Factor on ITV, which was seen by 7.7 million people.
But Strictly Come Dancing was Saturday night's most popular show, peaking at 11.7 million viewers (10.6m average).
The Day of the Doctor was broadcast in 94 countries at the same time as it aired on BBC One on Saturday night - earning it a Guinness World Record as "the world's largest ever simulcast of a TV drama".
Featuring three Doctors - Matt Smith, David Tennant and John Hurt - it delved deep into the character's psyche over 75 minutes.
Amid the special effects and multiple time zones, critics were particularly impressed with the interplay between the actors.
The Telegraph's Ben Lawrence wrote: "Tennant is edgy and mercurial, likely to turn on a pin. Smith is gentler, with a boyish eccentricity and other-worldly strangeness. They sparred terrifically with a fair amount of trademark humour.
"Smith's Doctor teased Tennant's about his 'sand shoes' and his weight. 'Ooh. That is proper skinny. Hello matchstick man!'
"And yet they were both skilled enough to convince the viewer that they were one and the same person, both sharing a compassion, an acute intelligence and a formidable nose for danger."
In a five star review, the Mirror's Jon Cooper singled out writer Steven Moffat as the real star.
"He's put something together here that not only gives hardcore fans a beautiful reinvention of their favourite show but also gives casual viewers a stonking story and a reminder why we all love this show so much," he wrote.
"This had labour of love stamped throughout it," agreed Simon Brew on the Den Of Geek website.
"It felt like a real treat, a gift to Who fandom, but more importantly, a strong episode in its own right."
Opening with the show's original credit sequence from 1963, the special featured the Daleks and the return of rubber suited, shape-shifting aliens the Zygons, who first appeared in 1975.
But the principal villain was potentially the Doctor himself.
Moffat's story played with the idea, introduced when the science-fiction show re-launched in 2005, that the Doctor was the "last of the Time Lords".
It transpired that Hurt's version of the Doctor had committed mass genocide in order to halt a "Great Time War" - and the 75-minute episode saw him fighting to come to terms with that decision, aided by two future versions of himself.
There were also cameos from former star Tom Baker, and Peter Capaldi, who replaces Smith later this year.
"The last few minutes affected me quite deeply," wrote Neil Perryman on the Guardian's website.
He conceded that some of the details "didn't make a lot of sense on first viewing" but added: "I don't care - I'll be watching it again this evening".
Speaking immediately after the broadcast, star Matt Smith said: "I think what's really clever about it is that what he [Moffat] has managed to do is change the mythology of the character - which, after 50 years, is an achievement."
Aside from the emotional drama, the episode was filled with comedic moments - including a proposal, a marriage and "a machine that goes ding".
"Is there a lot of this in the future?" John Hurt asked as David Tennant kissed Queen Elizabeth I.
"There is a bit, yes," deadpanned Matt Smith.
The UK viewing figures are the science fiction programme's highest since the 2010 Christmas Special.
They do not take into account people who taped the show, or watched it later on iPlayer - and are therefore likely to rise once consolidated figures become available.
Accepting the show's Guinness World Record, Moffat said: "For years the Doctor has been stopping everyone else from conquering the world. Now, just to show off, he's gone and done it himself!"
Tim Davie, from BBC Worldwide, said: "We knew we were attempting something unprecedented in broadcast history, not only because Doctor Who is a drama, unlike a live feed event such as a World Cup football match or a royal wedding, but because we had to deliver the episode in advance to the four corners of the world so that it could be dubbed and subtitled into 15 different languages.
"If there was any doubt that Doctor Who is one of the world's biggest TV shows, this award should put that argument to rest".
The global broadcast included 3D screenings in more than 1,500 cinemas in 94 countries - from Russia to Ethiopia.
They attracted hundreds of fans in fancy dress, including bow ties, fezzes and Dalek outfits.
A gala event at the BFI in London was attended by Smith, Hurt, Moffat and their co-star Jenna Coleman.
They received a huge cheer as the end credits rolled, while Tom Baker's surprise cameo also received a large round of applause.