Bayern’s hopes of a second treble in three seasons were ended on Tuesday night after losing the DFB Pokal semi-final penalty shoot-out 2-0 after a 1-1 draw with Borussia Dortmund.
Lewandowski, who has scored 23 goals this season, was taken to hospital after suffering a knock to the head following a goal-mouth collision with Dortmund’s goalkeeper Mitchell Langerak late in extra time.
“He’s gone to hospital, I don’t know how serious the injury is or if he can play against Barcelona,” said Bayern coach Pep Guardiola.
Robben, who has netted 19 goals this season, lasted just 16 minutes on his second-half come-back after a month out with torn stomach muscles and limped off with a calf injury.
“He’s injured too,” confirmed Guardiola, with more details expected on Wednesday.
Bayern’s attacking midfielder Thiago Alcantara is also facing a race to be fit to play against his former club Barcelona having come off with a knock to the leg.
The 24-year-old has only recently returned after more than a year out with back-to-back knee injuries.