Pierre-Emile Hojbjerg has completed his move to Tottenham from Southampton, who have signed Kyle Walker-Peters from the north London club on a permanent deal.
The Denmark midfielder has signed a five-year contract at the Tottenham Hotspur Stadium after the clubs agreed a transfer reported to be worth £15million ($27M AUD) plus bonuses.
Hojbjerg completed a medical on Tuesday and becomes the first signing of the transfer window for Spurs boss Jose Mourinho.
He moved to Southampton from Bayern Munich in July 2016 after struggling to break into the first-team picture at the Bundesliga giants.
The 25-year-old had made over a century of league appearances for the Saints but was stripped of the captaincy in June after it became clear he was not willing to renew his contract at the club.
Everton were credited with an interest in Hojbjerg but it soon became clear Tottenham were favourites for his signature.
Walker-Peters has moved in the opposite direction for a fee starting at around £12m ($22M), with the full-back having spent the second half of the 2019-20 season on loan at Southampton.
He has signed a five-year contract at St Mary's and coach Ralph Hasenhuttl was pleased to get the deal over the line.
"He is a very good fit for our style. He is a young, intelligent player, and he is very good on the ball, with good quickness and an ability to play this intense style that we like," said Hasenhuttl.
"I am very pleased we have been able to bring him back as our player, as this is a position that we have been looking to improve in and Kyle does this for us. I think he can develop his game even more here too."
Walker-Peters said: "I'm delighted to have signed here. The last few months on loan have been great for me and a lot of fun too. I've really enjoyed my football, the atmosphere here and also the style of play.
"I feel like I've already developed in the time I’ve been here, and that's a big part of wanting to stay too.
"Obviously, it's a club with a great reputation for improving young players and, personally, I've found it really valuable working under the manager, with his ideas on the game and what he expects from you as an individual."