Award-winning drama Lost attracted an audience of 3.9m as it returned to British television for a second series.
Matthew Fox plays one of the main characters in the serial
But the US show, which focuses on a group of aircrash survivors stranded on a desert island, failed to match its first series debut of 6m viewers.
The double bill, shown on Channel 4 on Tuesday, saw its audience slip to 2.8m after the first hour.
The drama, made by ABC, has been a hit on both sides of the Atlantic and won six Emmy awards last year.
The show commanded more than 20% of the total viewing audience during its two-hour slot on Tuesday, with Channel 4 showing episode one and two back-to-back.
Around 700,000 viewers then tuned into Channel 4's digital sister station E4 to see the third episode of the series.
The programme became the most successful US debut on Channel 4 when its opening season began last year.
It suffered only a slight dip to 5.9m viewers after two episodes were split by Big Brother.
The double bill, which cost $10m (£5.5m) to make, may have benefitted from having an edition of the popular reality TV show slicing it in half when it was aired last August.
In the US, the drama became a regular ratings winner, with 21m viewers watching the first season finale - up 3m on its debut.
Lost's second season debut in the US attracted an audience of more than 23m viewers.