Ajax have signed Steven Berghuis from Feyenoord on a four-year deal, the club announced on Monday.
Ajax and Feyenoord are the biggest clubs in the Netherlands and Berghuis's move has caused controversy due to rivalry between the two sides, especially between their fans. For several years, away supporters have not been allowed at matches between the Eredivisie clubs.
The 29-year-old had been a key player for Feyenoord in the last few seasons and was in the team when the Rotterdam side became Champions in 2017, for the first time in 18 years
Berghuis, who was under contract with Feyenoord until mid-2022, said in a statement that he wanted to move to develop his game further.
"I am 29 years old, and it's no secret that I wanted to take the next step," Berghuis said.
"It is important to me to further develop myself in the sport. When making the choice for my new club, in addition to my development as a football player, I was very much looking for the combination of playing for trophies, playing in the UEFA Champions League and staying in the picture with the national team. At Ajax I think this all coincides."
The winger began his professional career at FC Twente in 2011 and played for VVV-Venlo, AZ and Watford before moving to Feyenoord in 2017.