The opening episodes of Doctor Who spin-off Torchwood drew the largest digital channel audience for a non-sport programme, says the BBC.
Torchwood follows secret agents battling human and alien enemies
The first two instalments of the series, starring John Barrowman as Captain Jack Harkness, also attracted BBC Three's largest ever audience.
The 2100 BST episode had 2.4 million viewers and a 12.7% audience share, the 2145 BST one had 2.3 million (13.8%).
Two football matches in 2004 and 2005 earned larger digital TV audiences.
BBC Three controller Julian Bellamy said the audience figures for the new sci-fi series were an "incredible achievement".
"I'm delighted that last night's Torchwood was such a big hit," he said.
The series follows a team of investigators solving alien and human crime and is aimed at an adult audience.
It has been written by Russell T Davies, who scripted the comeback series of Doctor Who as well as earlier hits including Queer as Folk and Bob & Rose.
Torchwood is set in Cardiff and also stars Welsh actress Eve Myles as Gwen Cooper.
The first two episodes will be repeated on BBC Two on Wednesday.