Arsenal will face Villarreal in the Europa League semi-final after a comfortable second-leg win over Slavia Prague.
The Gunners, who were pegged back to a 1-1 draw late on at the Emirates Stadium last week, cruised to victory in the Czech capital.
Nicolas Pepe put Mikel Arteta's team ahead on the night, before Alexandre Lacazette and Bukayo Saka rounded off a six-minute onslaught from Arsenal.
Lacazette then scored in the second-half for the Gunners, who were brilliant on the night, to make it 4-0.
Meanwhile, Spanish side Villarreal comfortably saw off the side that beat Tottenham - Dinamo Zagreb - 3-1 on aggregate.
Goals from Paco Alcacer and Gerard Moreno ensured a relatively comfortable night for the side managed by former Arsenal boss Unai Emery.
This now means that it will be Arteta against his predecessor in the last four of the European competition.
Emery was in charge at the Emirates Stadium for not much longer than 12 months and was sacked due to the side's poor form - with a winless run of seven games for the north London club.
The now-Villarreal boss was replaced by Freddie Ljungberg, who took over on an interim basis, before Arteta was appointed as the Gunners manager later down the line.
Arsenal fans have been reacting to the reunion on Twitter, following their side's dominant performance in Prague.
Before the Gunners face the La Liga outfit in the last four of the competition, there are two Premier League meetings with Fulham and Everton - both at the Emirates.
Arteta's main chance of securing Champions League football next season on the red side of north London is through winning the Europa League but they will have to get past Emery's Yellow Submarine first.
