As HSV announced on Saturday, the Danish national team attacking player suffered a muscle tear in his right thigh during Thursday's 2-3 Nations League defeat in Norway. Albert Gronbaek will be sidelined for at least the next few weeks.
The club did not specify specifically how long Gronbaek will be out for. HSV travel to TSG Hoffenheim in the league on 10 October.
Two assists against Cologne
Gronbaek set up both of his team's only goals of the season in last weekend's 2-1 win over 1. FC Köln. The midfielder had scored twice in the German Cup tournament against SC Verl (3-1).
Gronbaek came on in the 82nd minute for Denmark in the Nations League clash in Oslo and left the pitch with his thigh bandaged after the final whistle. The 25-year-old will miss both matches against Wales, on Sunday and the following week, as well as the clash with Portugal on 1 October.