Bolton defender Marcos Alonso is set to 1 win over Blackburn on Tuesday.
Alonso missed almost four months after breaking his foot in a Carling Cup match in August and had just returned to action to make his first start last weekend.
But Bolton manager Owen Coyle has revealed that Alonso suffered a setback to the same foot on Tuesday, meaning he will miss more time.
"There was no new fracture as such, but the pin that was inserted to heal the original fracture has taken a knock and that needs to be replaced," Coyle said.
"He is set to be out for six weeks but we are hoping it will be less than that. We can't be sure right now because the operation will take place today and we will take it from there."
The 20-year-old appeared in nine games in all competitions for Wanderers last season.