Delivery Saver customers were able to book a Christmas delivery slot from 6am, but some complained the queue was opened before the advertised time, and they were kicked out of line.
People hoping to bag themselves a Tesco Christmas delivery slot have been faced with an online queue of nearly 300,000 people this morning.
Not only has the wait been extremely long, but shoppers have also had to struggle against a crashing website, with some reporting that they were booted out of the supermarket queue as soon as they got to the front.
Delivery Saver customers were told they could book a slot from 6am on Tuesday, but several people complained the queue was opened before the advertised time.
Posting on Twitter, one customer said: "I logged on at 5.59 (am) to get ready, only to find over 135,000 in the queue already."
By 6.13am, users were posting screenshots that showed the queue was up to 180,000 people.
That figure jumped to more than 287,000 a couple of hours later.
Another Twitter user said they spent time waiting in the queue only to be kicked out, writing: "Hey @Tesco just sat for half an hour in your xmas queue and as soon as I reached the front of the queue I got kicked out and now the wait is an hour."
Another said: "I was 38,000 in the queue and the app 'refreshed' itself, and now I'm number 178,000. You're having a laugh."
A Tesco spokesperson said: "We're currently seeing a high number of visits to our website and groceries app and some customers are temporarily having difficulty logging on or placing orders.
"We're really sorry about this. There are still slots available for both home delivery and click & collect over the Christmas period and we're working to get things back up and running as quickly as we can. In the meantime, we recommend that customers use our website to place their order."