Manager Steve McClaren's exhortation that "50,000 Geordies will demand a performance of attitude, character and football" evidently got through to his players as Newcastle dominated proceedings, forcing Ben Foster into a series of fine early stops.
Cheick Tiote struck from 25 yards, only to have his goal disallowed for Mitrovic being offside but with the crowd still muttering, there was no doubt about the Serb's composed 32nd- minute winner after being set up by Jonjo Shelvey.
New signing Andros Townsend hit the post amid United's incessant pressure and was given a standing ovation by the home fans when substituted but Newcastle nearly paid for their profligacy when Albion's Salomon Rondon fluffed his lines in front of goal in stoppage time.
(Reporting by Ian Chadband, editing by Ed Osmond)
