Warren Gatland says that Wales' medical team are confident Cory Hill will be "up and training" for a pivotal World Cup clash against Australia.
The Dragons lock is suffering from a stress fracture in his leg and has not played since February, but Gatland has named him in a 31-man World Cup squad.
"Prav (Welsh Rugby Union national medical manager Prav Mathema) and the physio spoke to somebody from the (Welsh) FA. One of their players had a more clean break, and they got him back playing in 30 days," Gatland said.
Wales midfielder Joe Ledley suffered a minor fracture of his leg playing for Crystal Palace against Stoke in May 2016, and 35 days later featured as a second-half substitute in his country's opening game of Euro 2016 against Slovakia.
"Cory this week goes down to Swansea to use an oxygen chamber, and he is on a plan now where we de-load him for a few weeks.
"The disappointing thing is that if we had picked it up three weeks ago then he wouldn't be far away and he would possibly have been all right for this Ireland game (next Saturday), but nothing showed up on the original scan.
"They are confident that he will be up and training for that second game against Australia, and he is a pretty good athlete, so we are not worried from a conditioning point of view.
"Cory is pretty important to the group with his experience and his lineout calling, and he did a great job as co-captain in Argentina last year.
"We felt that it is worth the risk. The initial conversations were that he would be back for Australia or Fiji, and I felt that if it was Fiji it might have been too much of a risk.
"That's why I have said there are some markers that will be put down. Hopefully he hits those markers over the next few weeks and we know that we are on track for Australia (on September 29)."
While Hill battles back to fitness, 21-year-old Saracens prop Rhys Carre has received Gatland's World Cup call after just 40 minutes of Test rugby against Ireland in Cardiff on Saturday.
Experienced international front-row forwards Rob Evans and Samson Lee did not make the cut, with Gatland naming ex-Cardiff Blues forward Carre, Nicky Smith, Wyn Jones, Tomas Francis and Dillon Lewis as his props for Japan.
"He is 128kg and is a big man, so he is only going to get better and better," Gatland added.
"I've just seen someone who has come in, had his eyes opened, and the progress that he has made over 13 weeks is phenomenal.
"It's about the fact that he has taken part in every training session and we have seen some huge improvement, so that if called upon he can do a job for us.
"He (Carre) is going to make mistakes, but if a guy comes in at 138kg and is really struggling, and by the end of Turkey (Wales' training camp last month) he is beating the other props in terms of fitness, then you have to take your hat off to him.
"He's got some engine on him, he is explosive when he carries the ball, and I thought he was good in that area yesterday.
"The thing I've found frustrating in this role over the years is the pressure the (Welsh) regional coaches have been under to get results and performances.
"That's often meant youngsters haven't been given opportunities, and that's been hard. The thing when you pick a youngster is you know you are going to go through some pain.
"You need to see the long-term development, and often we haven't seen that in Wales because of results. That's something we need to address and be aware of."