Brighton have signed midfielder Aaron Mooy from Championship side Huddersfield on a season-long loan.
But the Australian, 28, has signed a new three-year contract with the Terriers, running until 2022.
Huddersfield say Mooy has joined Brighton to "pursue his ambitions of playing in the Premier League".
Mooy played 29 times for Huddersfield in the Premier League last season, scoring three goals, but could not stop their relegation to the second tier.
Huddersfield head coach Jan Siewert said: "Aaron was adamant that he wanted to test himself again in the Premier League when Brighton's interest came in, and we didn't want an issue where we had a disillusioned player on the pitch in the final year of his contract.
"We had to look after the interests of Huddersfield Town and couldn't let him leave on a free at the end of the season, so him signing a new contract ahead of his loan move gives the club and the player possibilities for the future."
Mooy joined the Terriers from Manchester City in 2017 for a then record fee of £8m.
His original deal at Huddersfield had been due to expire in 2020. His new contract also includes the option of a further year.
Mooy has scored 11 goals in 120 appearances for the the Terriers.
Brighton boss Graham Potter said: "We are delighted to welcome Aaron to the club. He has played very well over the past two seasons in the Premier League, and will bring a different option and added competition to our midfield.
"He's been a talisman for Huddersfield in recent seasons with his performances on the field and he's proved to be an excellent professional both on and off the pitch.
"I'm looking forward to working with him. He is another good addition to our squad ahead of the new season."
Meanwhile, Brighton have signed French right-back Romaric Yapi from Paris St-Germain.
The 19-year-old has signed a one-year deal and will join the under-23 squad.
Find all the latest football transfers on our dedicated page.