Alonso will undergo surgery on Friday to replace a pin in his foot.
The Spaniard sustained the injury during Bolton’s clash with Blackburn at Ewood Park on Tuesday.
Bolton boss Owen Coyle said: “There was no new fracture but the pin put in when they did the operation to heal the original fracture took a hit and needs to be replaced so he could be out anything up to six weeks but we’re hoping for earlier than that.
“The operation will happen today and we’ll take it from there.
“He came in for the Fulham game the other night and looked assured and destined for a big future.
“I said to him he can handle the level and be comfortable in the environment so when he comes back he’ll be able to kick on with his career.”
