McClaren will have only four senior match-fit defenders to choose from - Daryl Janmaat, Chancel Mbemba, Fabricio Coloccini and Jamaal Lascelles - and not a single specialist left-back at his disposal at Vicarage Road, as he looks for priceless back-to-back Premier League victories.
The loss of Paul Dummett and Jack Colback, the man who filled in at left-back when the former was forced to leave the pitch against West Ham last time out, to hamstring injuries has compounded a casualty list which already included Massadio Haidara, Kevin Mbabu and Mike Williamson.
McClaren said: "Kevin Mbabu is out, Dummett has a tight hamstring, Colback deputised at left-back - he has a little niggle which we will not take a risk on. We have four fit defenders.
"Steven Taylor will be in the squad and probably on the bench. In terms of balance, it is very difficult, but we will find a solution somewhere and players will have to step in and do a job."
Taylor's inclusion comes after a five-month injury lay-off which has left him desperately short of match fitness, and McClaren will be keeping his fingers crossed that there are no further mishaps against the Hornets.
He is likely to have to be creative and faces a choice between playing one of his central defenders out of position, asking a midfielder to slot in at left-back or switching to a three-man defence.
Watford have lost their last four league games, but have beaten Newcastle twice already this season, on Tyneside in the league and at home in the FA Cup on January 9, a run McClaren is determined to see come to an end.
He said: "They are at home and have beaten us twice, they will be confident. We have a determination to turn that around. Watford are dangerous opponents, but it is about what we do."