Forest suffered their worst home defeat of the season and were totally outclassed by a strong Leeds side that gave Forest a lesson in how to play football.
Leeds totally dominated the first half putting two goals past Forest, but they could easily have gone in four goals up at the break, with Forest not having a single shot on goal.
It just got worse in the second half with Leeds doubling their tally and Forest were effectively down to nine men by the end of the game, with Andy Reid sent off for two yellow cards and Joel Lynch injured and only able to limp around the pitch.
Leeds looked dangerous from the start as they pushed forward in the early stages with Robert Snodgrass threatening when he got past a couple of Forest players before Joel Lynch did well to intercept.
A shot from Jonathan Howson just outside the area was drilled low and hard but straight at Lee Camp.
Snodgrass looked dangerous again when he was given too much space to get forward down the right but his cross was high and went over Aidan White at the back post.
Camp had to make the save again, parrying the ball away when Michael Brown got a shot in from 25 yards.
A good ball from Andy Reid sent Paul Anderson away down the left but his cross was met by the Leeds keeper and a defender.
Forest started to put some promising football together and another good move involving several Forest players ended when Reid chipped the ball towards the penalty spot, but too early for Marcus Tudgay to get on the end of it.
Leeds were soon back on the attack and took the lead when Camp sent the ball out to the left where it came off Greg Cunningham's head to Guy Moussi who lost it under pressure. Clayton won it and sent the ball to Snodgrass who, from the edge of the penalty area, buried it low past a diving Camp.
They should have been two up following a long ball into the box which Camp came out to chest away from Snodgrass, but he ended up sending it into the Leeds player and only a fantastic block from Moussi prevented the ball from going into an open goal.
Forest reacted with a good push forward and a superb ball in by Reid gave Robbie Findley a chance, but he was unable to get his shot on target.
Leeds missed yet another chance when Forest got in trouble at the back and again it was Snodgrass who caused problem, taking the ball off Cunningham and getting a good cross in, only for Howson to send the ball wide.
But they found the target again in the 45th minute when Luciano Becchio headed the ball over Lynch to Howson who, in too much space, belted the ball into the top corner from the edge of the box.
Findley, who had not had a good first half, made way for Ishmael Miller, returning from injury, at the start of the second half.
But Leeds had another goal four minutes from the start after a superb cross was whipped in from the left by Brown. Becchio timed his run in perfectly and sent a glancing header in, giving Camp no chance to stop it.
Forest had a rare chance from a long ball forward by Camp which Miller controlled, turned and fired from just inside the penalty area, but it was deflected over the bar for a corner.
And they produced some good football when Tudgay picked out Anderson who found space to cross neatly to Miller, but he sent the ball straight at the keeper from six yards out.
A double substitution saw Chris Gunter and David McGoldrick come on for Cunningham and McGugan.
Seconds later Leeds were four up when Moussi slipped, allowing Howson to get the ball. Camp couldn't hold it and parried clear, but Clayton was first to the ball to tuck in the rebound.
A great ball in from Lynch from the left came close to getting a consolation goal for Forest when, with Alex McCarthy beaten, the cross skimmed the top of the crossbar.
With all three Forest substitutes used, Lynch looked like he was struggling to continue and although he stayed on the pitch he was not able to make a full contribution.
And when it looked like it couldn't get any worse Reid, sliding in and missing the ball, picked up his second yellow card and Forest were down to ten men.
Camp, Chambers(C), Morgan, Lynch, Cunningham(Gunter 64min, Anderson, Moussi, Reid, McGugan(McGoldrick 64min), Tudgay, Findley(Miller45minHT)
Subs not used: Smith(GK), Greening
Bookings: Lynch 51min, Reid 64min, 79min RED CARD
, Morgan 68minLeeds United:
McCarthy, Connolly, Kisnorbo, Brown, Becchio(McCormack 75min), Howson(C), Clayton(Keogh 75min), Pugh, Lees, Snodgrass(Nunez, 80min), White
Subs not used: Taylor(GK), Bromby
Scorer: Snodgrass 20min, Howson 45min, Becchio 49min, Clayton 66min
Referee: D Deadman
Attendance: 23,577 Away attn: 3,597