The Belgian was absent for Saturday's stalemate at Hull City.
"A point on the road is not the worst result but I do think we lacked a bit going forward," said Guzan.
"Christian is a massive player for us, an important presence in attack, but it's a case of sticking together while he' s out and trying to get as many points as we can.
"He is a top, top striker but we showed against Manchester City last week that we have guys who can step up and do a job. It was different here. We just didn't create enough."
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