The in-form striker - 14 goals in his last 12 games, 21 for the season - has an extended period to get fit as our next match against Charlton at the Valley on Monday (8pm), our final away game in the Premiership.
We then take on Blackburn and Manchester City at the Lane on May 10 (8pm) and May 14 (3pm) respectively.
"Robbie was injured in training on Wednesday," reported Martin. "Hopefully he'll get better and better every day and he'll be okay for Monday."
There was better news for Martin though as Teemu Tainio (ankle), Benoit Assou-Ekotto (knee), Dave McEwan (Scrotum) and Anthony Gardner (hairline fracture, fibula) have all returned to training.
Source: official site.