City boss Mark Hughes had hoped to pitch the Brazilian striker into Tuesday's Carling Cup clash at home to Scunthorpe but after already spending two months on the sidelines, it is now likely the 25-year-old will not be available until the City of Manchester Stadium clash with Burnley on November 7.
"He's had a little bit of a setback, and the likelihood is it will be another 10 to 14 days," confirmed Hughes. "The area where the stress fracture is hasn't healed as quickly as we anticipated."
He added: "He could probably join in with the group, but the fear would be if he got a direct bang on that area there's a chance he may re-break the leg.
"So we don't pitch him into those circumstances, and it would be crazy to, so we're going to err on the side of safety.
"We've options, so can cope and give Robi the time he needs. It's important we don't put him at risk."