AFP - A fractured foot means Real Madrid's Toni Kroos is the latest Germany star ruled out of Friday's 2018 World Cup qualifier away to San Marino.

The 26-year-old misses the qualifier, four days before Germany's friendly against Italy in Milan, with a hairline fracture of the metatarsal bone.

According to Spanish sports daily Marca, the German international may need surgery and could be ruled out for up to three months.

He suffered the injury in Sunday's 3-0 Spanish league win over Leganes and can not train for the next 10 days, the German Football Association (DFB) announced on Tuesday.

Kroos had the injury confirmed after a scan in Munich with the national team doctor Hans-Wilhelm Mueller-Wohlfahrt.

The attacking midfielder joins centre-back Jerome Boateng, who was forced out of Germany's qualifier after injuring his groin and right knee in Bayern Munich's 1-1 draw with Hoffenheim on Saturday.

Both Kroos and Juventus' Sami Khedira were only called up for the qualifier against San Marino, ranked 199 places below Germany by Fifa, in Serravalle before being released to their clubs.