The Terriers are looking to beat Premier League rivals Newcastle United and Southampton to the signing of the Belgian player, with Bundelsiga club RB Leipzig also reported to be interested.
The winger, who has been capped once for the Belgian national team, scored 6 times in 39 appearances for his club during the last campaign.
Huddersfield have already strengthened their attacking options this summer with the signing of Egyptian player Ramadan Sobhi from Stoke City last week for £5.7 million.
The Yorkshire-based team also broke their club-record fee for Monaco defender Terence Kongolo ealier in June, after the player had a successful loan spell.
David Wagner's men will hope to improve on their first season in the Premier League, which saw them finish in 16th position having scored just 28 goals all season, the joint-worst tally in the division.