"Losing the premier half-back in the northern hemisphere was a blow," said Johnson. "He has injured his AC joint and he certainly won't be available next week, that's for sure. The boys who have come back from the Lions tour have had a hard year and he will be glad of the rest."
Without Peel, Wales still moved into a 15-5 lead with tries from Stephen Jones and Mark Jones before losing all composure against a determined Azzurri effort. Italy were rewarded with a score for full-back Ezio Galon and then levelled the half-time scores at 15-15 with Pablo Canavosio's breakaway try.
No side has dropped Championship points at home to Italy since they were admitted to the RBS Six Nations in 2000. But things could have been worse for Wales had Italian fly-half Ramiro Pez not endured a miserable day with the boot and missed three penalties and a conversion.
Captain Michael Owen said: "The first half was really good, we had loads of chances but didn't finish them off and I couldn't believe we went in at 15-15. In the second half we never really got going and we got what we deserved."
Johnson added: "Fair play to the Italians, they played their hearts out. They were brave, as they have been all tournament."
Johnson insisted Wales's poor performances against Ireland and Italy are not due to the departure of head coach Mike Ruddock last month. "I put all that speculation aside. The preparation has been first class and you can only judge it on that," he said. "From my perspective the players have been buoyant, they have been good and done everything coaches asked.
"You can't ask more of individuals. They haven't been walking around sour, I don't need to motivate them. They are just not playing well. We have had a few disruptions but we have to get back on this horse."