Incredibly when Gareth Southgate got the sack Middlesbrough were just one point behind Newcastle, now they are 20 points in arrears and in 14th position.
Despite the weather, the attendance of 46,964 smashed the previous Championship record held by Sunderland.
This was the first time since 1991 that United entertained Boro outside of the top-flight and both sides made four changes.
With just one win to date for Boro, the omens were not good for Gordon Strachan who had never won in eight attempts as a manager on Tyneside - losing seven of those.
The first chance fell to Boro after 11 minutes, Leroy Lita heading over as he looked to add to his five goals this season.
But it was United who took the lead after 16 minutes and Boro were furious.
After Dave Kitson crudely challenged Alan Smith, Danny Guthrie's free-kick saw Ameobi appear to push Emanuel Pogatetz and when the ball broke Harewood reacted first from close range.
Boro were close to a 34th minute equaliser when a swerving Gary O'Neil free-kick was parried by Harper and Aston Villa loan player Isaiah Osbourne's shot hit the hand of Steven Taylor and then off the face of Harper and on to the post, before the keeper gathered.
Brad Jones was lucky after 53 minutes when his attempted clearance cannoned against Harewood and just wide of the empty goal.
Harewood then missed a sitter from two yards, while at the other end David Wheater headed inches wide after 57 minutes.
And within 30 seconds Newcastle doubled their tally, Ameobi climbing above Wheater to head in Guthrie's right-wing cross to make it six goals in six league games this season from the striker.
Harper in his seventh Tyne-Tees derby had little to do in the second half and the visitors were totally deflated after United's second goal went in.