A brilliant display by Forest kept their automatic promotion hopes alive and, with Bristol City losing at Millwall, it all goes down to the last game of the season.
There was an early set-back for Forest when Leyton Orient took an early lead. But after that Forest dominated the first half, getting two goals in the process.
Forest looked comfortable throughout the second half and added to their tally just before the hour mark.
After a slow start Leyton Orient took the lead after Adam Chambers fed the ball through to Matthew Lockwood who was unmarked on the left. He took a couple of paces and hammered the ball into the roof of Paul Smith's net from 15 yards out.
Ten minutes later Forest were back on level terms with a great goal from Jack Lester. He found space in midfield, shook off the challenge of Luke Guttridge, put the ball round John Mackie and shot from 15 yards into the bottom corner past the outstretched arms of Glyn Garner.
And Lester almost made it two when he ran 30 yards to beat Lockwood. The ball came off an Orient player and came back out to Lester as he sprinted into the penalty area to follow up with a shot which forced an excellent save from Garner, diving to his right.
But Forest were soon in the lead following a quickly taken free kick and more superb work from Lester. Kris Commons found Lester, who held the ball up and laid it back to Commons, who sent the ball low into the corner of the net.
Forest continued to dominate the game and were allowed plenty of space by Orient while Paul Smith had only one easy save to make.
Commons and Lester combined well again, slicing through the Orient defence, but this time the final ball from Commons was poor.
Gary Alexander had a chance to equalize late in the half when he got in between Ian Breckin and Luke Chambers, but blazed over the bar and sent the ball flying into the street beyond.
Forest had a chance in stoppage time when Lewis McGugan found Grant Holt, who had a clear run on goal, but Adam Chambers made a run back to block his effort and Holt's shot went out for a corner.
Forest came close to a third in the opening minutes of the second half. The ball came in from Commons' corner, missed Breckin but found Grant Holt, whose glancing head had Garner diving to his right to get a touch on the ball to just keep it out.
But the third wasn't long coming, from a free kick over 30 yards out and it was again the combination of Commons and Lester that were responsible. Commons faked a shot but lofted the ball over the wall and into the penalty area to Lester who sent the ball flying under the keeper from 6 yards.
As Forest continued to push forward David Prutton had a shot deflected, giving Garner a chance to gather up the ball before Lester could get on the end of it.
And John Curtis could have scored from a quick corner when he had Garner beaten but his effort went just wide of the post.
The away supporters when wild when the news came in that Millwall had scored against Bristol City and the party atmosphere was in full swing.
The rest of the game was almost irrelevant and although Orient finished more strongly Forest comfortably held onto their lead.
Nottingham Forest: Smith, Curtis, Chambers, Breckin(C), Wright, Perch, McGugan(Gary Holt 76min), Prutton, Commons, Grant Holt(Dobie 70min), Lester
Subs : Pedersen, Bennett, Bastians,
Bookings: Chambers 45min, Prutton 83min,
Scorers: Lester 18min, 59min, Commons 29min,
Leyton Orient: Garner, Barnard, Lockwood(Echanomi 72min)Mackie(C), Tann, Chambers, Thelwell, Guttridge, Tudor(Corden 65min), Alexander, Jarvis(Hooper 65min)
Subs: Morris, Miller,
Bookings: Gutteridge 33min, Chambers 57min,
Scorer: Lockwood 9min
Referee: Keith Hill
Attendance: 7,206 away attn: 1,405
