Kemar Roofe ensured Leeds United will hold the advantage heading into the second leg of the Championship play-off semi-final clash between Leeds United and Derby County.
Here, we take a quickfire look at some of the talking points from Pride Park:
1 - The Shack Attack
It was quite a showing from the 19-year-old.
Shackleton stepped off the bench in the 24th minute in place of the injured Adam Forshaw and Leeds never looked back.
He was back at the place where Bielsa handed him his Whites senior debut last August, with darting runs, high energy and pace to burn which terrorised the County defence.
The youngster provided Leeds with that extra spark in midfield and refused to be bullied by many around him who were beyond his years.
With Forshaw a doubt for Wednesday, and calls for him to be freed answered... this might just be the point of no return.
2 - Roofe is on fire (against Derby)
After nearly three months on the sidelines Kemar Roofe was back amongst the goals and tormenting Derby once again.
The striker bagged his 15th of the campaign, and his fourth against the Rams this season alone.
Jack Harrison's ball fed the 25-year-old the ball on a plate for a lovely first-time finish in the 55th minute to hand Leeds the advantage before the return leg.
More of that, please.
3 - It's never dull...
These two sides just can't get away from controversy.
United's lead looked to be under threat in the 78th minute as Jack Harrison and Jayden Bogle tangled inside the Leeds box.
Referee Craig Pawson pointed to the spot but after being surrounded by both sets of players, he consulted linesman Eddie Smart.
After a long discussion between the pair Pawson reversed his decision deeming Bogle to have pushed Harrison in the back before the pair hit the ground.
On replay, there didn't appear to be much in it either way. But it was a lucky escape for United.
Harrison said afterwards: "I was a bit surprised.
"I was only going for the ball, I had no intention to take him down or anything like that. We try and play a fair game and what happens happens.
"I felt he came from behind me but it’s all about perspective. That’s just my point of view, it could be different from everybody else.”
Mateusz Klich also received a yellow card for a confrontation with Derby defender Fikayo Tomori, which replays showed he aimed a headbutt at his midriff.
No retrospective action, though, can be taken against the Pole due to the referee dealing with the incident during the match.
4 - Manager reaction
Bielsa on the advantage...
“It’s an advantage but it’s not a decisive advantage,” Bielsa said.
“We still have 90 minutes to play and we only have a difference of one goal. If we take as a reference what happened in the last Champions League games, we shouldn’t draw conclusions about it.
"Every game is a new situation and I don't think the three games we’ve played (against Derby) guarantee us anything in the next game.”
Lampard on the penalty decision...
“The penalty is one which could go either way,” he said. “I think it was (a penalty) because Bogle gets his leg across his man.
“Contact was minimal but the astounding thing is that when the ref gives it, he’s the boss on the pitch but he consults his linesman. You think there’d be some big information which the referee hasn’t seen and I don’t think there is. It’s like VAR without the computer system.
“I’m not sure it’s a penalty but I’ve never seen a decision overturned unless there’s something clear which hasn’t been seen, and that’s not the case. If we all looked at it in this room, some would say yes and some would say no, I get that. I’m just surprised a referee in a game of his magnitude has decided to play second fiddle to his assistant.”
5 - A slender advantage
With the victory United earned themselves a slender advantage heading into the return leg.
Leeds will welcome Derby to Elland Road on Wednesday evening, with a spot at Wembley on the line.
Aston Villa took control of their tie with West Brom earlier in the day with a 2-1 victory and they will do battle once more on Tuesday night.
Leeds, though, are firmly in the driving seat and will be backed by a sell-out crowd in LS11.