Tottenham completed a Deadline Day coup by signing France international Moussa Sissoko just before the window closed.
The 27-year-old midfielder has signed a deal which will keep him at White Hart Lane until at least 2021.
Official confirmation of the deal emerged just after Sissoko posted a picture of himself on Twitter holding up a Spurs shirt, which he captioned: "Very happy to join Spurs for the next five years!"
At one point Everton appeared to be favourites to sign Sissoko but Spurs matched their £30m offer and the Merseyside club eventually withdrew their interest. Sky sources understand Everton boss Ronald Koeman tried to phone Sissoko, but the player did not answer.
Sissoko impressed for France at Euro 2016 but was unable to prevent Newcastle's relegation from the Premier League last season.
He has pushed for a transfer this summer after claiming it would be difficult to retain his international place if he was playing his football in the Sky Bet Championship.
Newcastle wrote in a statement on Wednesday night: "Midfielder Moussa Sissoko has completed his transfer to Tottenham Hotspur for an undisclosed fee.
"The 27-year-old France international arrived on Tyneside in January 2013 from Toulouse and made 133 appearances in all competitions for the Magpies during three-and-a-half years at St James' Park, scoring 12 goals.
"Sissoko's final outing for United came in a 5-1 victory over his new side, Spurs, on the last day of the 2016-17 campaign."