Leeds stole three points as Middlesbrough wasted a catalogue of missed chances.
The 3-2 defeat means Boro are now one off the bottom in the Premiership as they have taken just one point from their opening four matches.
After conceding a 16th-minute opener to Lamine Sakho, Boro then piled on the pressure and deservedly struck back with two goals in three minutes on the hour mark.
Szilard Nemeth first equalised, before Juninho struck an exquisite second, and from that point there looked only one winner.
Chances still went begging for the home team, but they were kept back 13 minutes from time when another of Reid's season-long French loan signings in Zoumana Camara headed home the Leeds equaliser.
With the game seemingly heading for a draw, 18-year-old Andrew Davies slipped as he was poised to clear a long Jermaine Pennant pass, allowing Mark Viduka to lob home the winner over goalkeeper Mark Schwarzer.
It was an unlikely victory for Leeds, but Reid said: “It was a great football match. There was a lot of great play, a lot of dull action and a lot of mistakes, but we got the breaks.''
“The young lad Davies had a smashing game and it always disappointing when you see someone slip like that, but then the one-on-one finish from Viduka was fantastic.''
“It says a lot about the character of the side when you concede two quick goals like we did at a difficult place to come.
“Boro put us under a lot of pressure, but we kept on going and the players are really pleased.
“We needed that one because we had forgotten how to win as a team and as a club, so hopefully that will change things around for us.''
Davies was understandably a distraught figure in the Boro dressing room following the match, but there were words of consolation from Boss Steve McClaren.
“He is devastated and blaming himself, but these things happen,'' said McClaren.
“He is only 18 and if you saw him at Leicester (in the goalless draw on
Tuesday) he produced an unbelievable performance, while today against Viduka and Alan Smith, one of the best partnerships in the Premier League, he played well above his tender years.
“Although this will be highlighted, even the best players make mistakes. He has got character to learn from it.''
McClaren was left shaking his head at how his side had failed to even take a point. He added: “My God, we had enough chances there to win three games.
“The performance was good as we have improved in every department, but when you look at the result it is with disbelief that we have come away without a win.
“Leeds started well, but from then on I thought we controlled the game, dominated and showed great character in coming back from a goal down to go 2-1 up.
“We had chances for a third or a fourth and even after it was 2-2 we had further chances to still win the game.
“This is one of those matches where you now have to go away and lick your wounds.''