Tottenham have confirmed their Premier League fixture with Manchester United on January 13 will be held at Wembley.
The club hope to schedule the required test events at their new home shortly, but will not be able to complete them in time for what would have been a prestige stadium opener in the middle of next month.
Their stadium was due to open earlier this season, having been initially put back from the summer, but has been delayed by issues with critical safety systems.
Tottenham confirmed on Wednesday that testing continues, and will continue over Christmas, and they will issue another update on a possible opening date in the first week of January.
The club's chairman Daniel Levy said: "We are acutely conscious that we are asking fans to go to Wembley for far longer than any of us wanted to. However we are now seeing the progress that we needed to see.
"What I don't want to do is set any firm dates until we have finally achieved a safety certificate. So many people tell me to look at other major schemes that run late and, whilst I know it happens often, we are still hugely frustrated.
"It is important, however, to recognise the sheer complexity of the scheme. It will be one of the first fully-integrated digital stadiums and will also be required to meet the latest and most stringent safety regulations.
"Once again I want to apologise to fans and to thank you for your ongoing support. We have a busy time ahead both on and off the pitch, particularly after last night's amazing qualification for the last 16 of the Champions League. What a memorable night. I should also like to take this opportunity to wish you and your families well over the festive break."