There was certainly a big atmosphere at the start of the match as Barnsley aimed to do the double over Leeds United.
It was the Reds that struck gold early in the game through Kieran Trippier's well taken free kick that decieved everybody and Shackell profited from a Danny Haynes knock on at the far post to tap it in with just two minutes on the clock to stun the Elland Road crowd and to ignite the Barnsley travelling fans.
It looked like O'Connor had got Haynes in behind the defence with just eight minutes of the game past, but he was fractionally offside. Leeds were quick to attack and Robert Snodgrass had a go from distance but blazed it high over the bar.
Leeds United had a prime opportunity with a free kick just outside the box. Max Gradel hit it superbly, but Luke Steele managed to push the ball onto the underside of the bar and it rebounded off his head and out for a corner. Thankfully the big video screen at Elland Road helped work out an amazing escape for the Reds.
Leeds were again left wondering how they had not equalised when Becchio found himself in space with just the keeper to beat, but he managed to hit the ball wide of the target.
Leeds did equalise midway through the half when Luciano Becchio rose highest to head home a corner which sparked the Elland Road fans into noise.
Barnsley and a chance to go back in front when Nathan Doyle put in a good ball for Trippier to take it to the byline. His cross fell for O'Connor, but he could only hit it over the bar on the volley.
Trippier was again showing great strength and pace when Shackell's high pass had the Manchester City loanee getting around the defence to put a teasing ball across the face of goal.
Leeds won a soft penalty when Max Gradel stormed into the area and appeared to be brought down in front of Luke Steele. Gradel took it himself and wrong footed Steele to put Leeds in the lead for the first time in the match with eight minutes remaining in the half.
The second half started with Doyle having been replaced by Jim O'Brien through injury&nbsp;and it wasn't long before Barnsley equalised with a great through ball for Matt Hill to hit home like a seasoned striker. Again the leeds crowd were stunned into silence. Definitely a goal to catch on Barnsley Player highlights.
Minutes later O'Brien won a great header that led to a race for the ball between Haynes and Schmeichel with the Leeds keeper just managing to win. Moments later a bad tackle from Bradley Johnson earned him a second yellow card and he was off and Leeds were down to ten men.
O'Brien put in a good ball across a packed goal mouth and Shackell wasn't too far away from converting a scissor kick attempt.
Leeds made a double substitution with 24 minutes remaining, bringing Davide Somma and Sanchez Watt on in place of Becchio and Snodgrass.
Max Gradel put Leeds back in front when a mistake at the back let him in behind the defence to shoot into the far post beyond the diving Luke Steele.
With 17 minutes remaining Mark Robins brought on Jacob Butterfield for Bobby Hassell in search of the equaliser.
As the tension grew on the pitch Max Gradel battling hard with Jason Shackell received a yellow card for appearing to stamp on Shackell's leg.
Schmeichel tipped an attempt from Arismendi over the bar as Barnsley pressed hard. Jacob Mellis earned a free kick in a very good central position 22 yards out after being brought down and Trippier's curling free kick left the keeper rooted to the spot to level the scoring once again. The Barnsley defenders were leading the way in the scoring.
Andy Gray came on for the final minute with Jacob Mellis coming off looking injured. With five minutes of added time to be played there was still time for either side to get a winner.
Barnsley pushed hard for the winner and put Leeds under pressure in their own half in the final minutes and O'Connor came close with a shot across goal going a couple of feet wide. It was the last chance in a thoroughly enthralling game with six goals.
BARNSLEY: Steele, Hassell (Butterfield 73), Shackell, Doyle (O'Brien 46), Haynes, Trippier, Mellis (Gray 89), McShane, Arismendi, Hill, O'Connor.
Subs: Preece, Lovre, Nouble, Bennett
LEEDS: Schmeichel, Bruce, Gradel, Kilkenny, Becchio (Somma 66), Howson, Johnson (sent off 52), Lichaj, Snodgrass (Watt 66), McCartney, O'Brien.
Subs: Higgs, Paynter, Parker, Bromby, McCormack
Barnsley: Shackell (2), Hill (48), Trippier (81)
Leeds United: Becchio (23), Gradel (37, 70)