About 200,000 shoppers were expected at the Bluewater Shopping Centre in Kent on Saturday as sales fever hit the UK.
Shoppers were queuing outside Bluewater from 0100 GMT
Stores opened from 0500 GMT but centre managers said about 1,000 bargain-hunters had been queuing up four hours before that.
They were predicting the record for the highest number of people visiting the centre in a day could be broken.
Nearly 100 of Bluewater's 331 shops were open on Boxing Day, with the whole centre open on Saturday.
Busiest day ever
Alan Jones, marketing manager for the complex, which is near Dartford, said: "This day last year was our busiest day ever and it looks as if we are going to beat that.
"The Next sale started at 0500 GMT and we had 1,000 people waiting at 0130 GMT.
"The car parks are full, so I would say there are 200,000 people in the centre.
"I think we will set the record today."
The centre has 40 cafes and a 13-screen cinema and some of the coffee shops and snack bars opened in the early hours to offer refreshments to the crowds of queuing shoppers.
A spokesman for AA Roadwatch said the nearby A2 and M25 had seen a build-up of traffic as people drove to Bluewater and he predicted more of the same when shoppers left later in the day.
He said: "People have spent two days in with their families and are now desperate to get out and do some shopping so the roads around Bluewater are looking very busy."