Newcastle manager Alan Pardew admitted the absence of Steven Taylor and Fabricio Coloccini cost his side dearly as the Magpies went down 4-2 to Norwich in the Barclays Premier League at Carrow Road.
Pardew started with James Perch and Danny Simpson at centre-back, but the inexperienced duo failed to handle Norwich's attacks, and in particular the physical threat of Steve Morison and Grant Holt.
"It's fairly obvious we missed them," Pardew said. "Our squad has been stretched to the limit."
He added: "Having three first team centre-halves missing is major. We did very well other than the set plays today. Morison and Holt are a handful and so was Hoolahan in behind. They gave us some tough times today.
"We expect to have one or two back next week and we certainly need them. We can't concede from three set plays and expect to win the game."
Like Newcastle, Norwich lost last week, going down 5-1 to leaders Manchester City. The league newcomers looked anything but short of confidence on Saturday afternoon, however, with Wes Hoolahan, Andrew Crofts and David Fox all impressing in support of Morison and Holt.
"I'm delighted to get that win after last week," Canaries boss Paul Lambert said.
"Newcastle are a good side. You can see that in how they have been doing in the league. They have a big threat up front. I thought we played very well and we deserved to win."
The Scot paid tribute to fans' favourite Holt, who has had to settle for a place on the bench for large parts of the season.
"He's as important as he was two years ago when I joined," said Lambert, whose team are now ninth in the table. "He and Morison were excellent today. I'm delighted with everyone's contribution."