Dallas returned to Channel 5 with nearly 3 million viewers on Wednesday, while new ITV1 drama Mrs Biggs debuted with just over 4 million.
The Us drama, back after 21 years with a mixture of new stars (Jesse Metcalfe) and old (Larry Hagman, Patrick Duffy) averaged 2.9 million viewers (13.1%) between 9pm and 10.15pm on Wednesday.
This was nearly double Channel 5's average share in the slot over the last three months.
Mrs Biggs, the Jeff Pope drama about the Great Train Robbery from the point of view of Ronnie Biggs' then wife Charmian, played by Sheridan Smith, had 4 million viewers between 9pm and 10pm, an 18.4% share.
The ITV1 drama was narrowly beaten by BBC1's Who Do You Think You Are?, featuring Annie Lennox, which had 4.1 million viewers (17.9%), also between 9pm and 10pm.
Over on BBC2 the last