FA CUP FINAL – The Welshman had a controversial role in Alexis Sanchez’s opener before heading home the late winner to defeat the ten-man Blues 2-1 at the national stadium.
The result also meant more history for under-fire boss Arsene Wenger as he became the first man to guide a side to seven FA Cups.
Following an impeccably observed minute’s silence for the victims of the Manchester terror attack, the drama soon got underway after kick off.
And the breakthrough arrived in contentious fashion.
Sanchez blocked N’Golo Kante’s clearance, possibly with his arm, and the ball sailed backwards into the Chelsea area.
The Blues defence stood and watched as Aaron Ramsey, stood yards offside, went to go for the loose ball before stepping aside for Sanchez to race onto and slot home.
The assistant referee immediately flagged for offside, but after consultation with the man in the middle, the goal was allowed to stand – much to the champions’ dismay.
Arsenal were flying now and almost doubled their advantage shortly after the quarter of an hour mark.
Mesut Ozil cut in from the right and side-footed the ball goalwards, but Gary Cahill was on hand to make a goalline clearance.
Antonio Conte was becoming more-and-more agitated on the sideline as his defence was being pulled all over the shop and they survived yet more danger minutes later.
Ozil whipped in a cross that was met by Danny Welbeck as he headed against the post, with the ball rebounding onto Ramsey and back onto the post.
Chelsea managed to regain their composure following the restart and were well on top before their chances of a comeback took a huge hint.
Having already been booked, Moses launched himself to the floor inside the Arsenal box while next to Nacho Monreal – but the eagle-eyed official spotted the dive and sent him packing.
Just as it looked like it was game over Costa drew he and his nine team-mates level with a scuffed shot following Willian’s assist – but the celebrations were shortlived.
Just two minutes later Ramsey struck with the hammer blow, heading home from Olivier Giroud’s cross to ensure the Cup will be back on display at the Emirates.