A further fifth-placed finish and decent run to the 2018–19 Belgian Cup Final - where they were beaten 2–1 by Mechelen despite having taken the lead - alerted clubs from across the border in Germany, particularly 1.

As part of a dynamic Great Old side under first Ivan Leko and then Frank Vercauteren, Verstraete helped Antwerp to a third-place finish in the 2020–21 season, the club's highest placing since their previous league title in 1957.

However, he was not allowed play in the covid-delayed 2020 Belgian Cup Final win over his former side Club Brugge, as he had not been signed by the time of the original date of the decider in April 2020.

The following season under Danish coach Brian Priske, Royal Antwerp finished fourth, after losing home and away to Anderlecht in the 2021–22 league championship play-offs.

On 6 September 2022, Verstraete joined Mechelen on loan,[1][2] helping them win their fight against relegation, and aiding their run to the 2023 Belgian Cup Final against Royal Antwerp.