Toni Kroos will miss Real Madrid's forthcoming matches with an adductor tear, the LaLiga giants have confirmed.
The Germany midfielder was substituted 10 minutes from time in Sunday's 2-0 loss to Real Sociedad at the Santiago Bernabeu, a result that left Santiago Solari's side fifth in Spain's top flight.
Madrid did not specify an expected return date for Kroos but his grade two tear is likely to mean an absence of around three weeks, according to Madrid-based Sports newspaper AS.
That means the 29-year-old will miss both legs of the Copa del Rey last-16 tie against Leganes – the opening match of which comes on Wednesday – and the league games against Real Betis and Sevilla.
Los Blancos close out January with a trip to Espanyol before entertaining Deportivo Alaves.
The February 9 derby at Atletico Madrid is followed by a trip to Ajax in the last-16 of the Champions League.
Kroos' absence adds to a considerable injury headache for Solari, who is currently without Gareth Bale (calf), Mariano (sciatica), Marco Asensio and Marcos Llorente (both hamstring).