The part Unai Emery played in Tottenham reaching Champions League final

Lucas Moura scored a hat-trick on a historic night for Tottenham [Courtesy]

Arsenal fans will no doubt have found Tottenham’s Champions League exploits hard to watch on Wednesday night.

Their fierce north London rivals pulled off a miracle as Lucas Moura's dramatic second-half hat-trick set up a stunning 3-2 win over Ajax - and meant they will face Liverpool in the final.

Spurs were dead and buried at half-time in the second leg at the Johan Cryuff ArenA as they trailed the Amsterdam team 2-0 on the night and 3-0 on aggregate after goals from Matthijs De Ligt and Hakim Ziyech.

However, a miraculous comeback, spearheaded by Moura, was completed deep into added time when the Brazilian slotted home a loose ball to seal away goals success and spark amazing scenes in Amsterdam.

And, to make matters worse, Emery was the man who sold the Brazilian to Spurs during the January transfer window last season.

The Spanish boss was in charge of Paris Saint-Germain and made the decision that the forward was deemed surplus to requirements in the French capital.

The Brazilian and Unai Emery worked together at Paris Saint-Germain [Courtesy]

So Lucas made the £23million switch to Tottenham and although he has endured a stop-start career in the Premier League, he delivered a heroic effort in Amsterdam to surely earn hero status at Spurs.

It’s undoubtedly a tough pill to swallow for Arsenal, who are preparing for the second leg of their Europa League semi-final in Valencia on Thursday night.

Spurs knew they did not have history on their side as only one of the 17 teams who lost the first leg of a European Cup semi-final at home had gone on to progress to the final.

They went into the break losing 3-0 on aggregate but Lucas somehow popped up with a remarkable second-half hat-trick to seal a memorable night for Spurs - not so much for Arsenal, though.