If all goes according to plan, UEFA will reform the European club competitions, which will see 128 clubs playing 647 matches.
Chelsea beat Eintracht Frankfurt in penalties, while Arsenal's path to the final was more straightforward, beating Valencia 4-2.
The Gunners travel to Emery's old club Valencia on Thursday defending a 3-1 semi-final, first leg lead given to them by the two star strikers at the Emirates last week.
Frankfurt, who are challenging for a top four spot in the Bundesliga and held Chelsea to a 1-1 draw at home last week.
A three-time winner of the competition with Sevilla, Unai Emery is on course for another Europa League final in his first season at Arsenal.
If Gameiro knows Arsenal, he knows Emery too, having played under the Spaniard at Sevilla, where they won the Europa League thrice.
The impact of missing out on the Champions League has had serious implications on the budget Emery has had to work with.
Ajax dominated the first half until Pochettino completely changed his game-plan by switching from a 3-5-2 formation to a 4-4-2 system.
It all started so well for Sarri as Chelsea kicked off the season with an 18-game unbeaten run in all competitions.
The Londoners doubled their aggregate lead just five minutes into the second leg of this quarter-final tie thanks to Pedro's neat finish after a one-two with Giroud.
Lacazette's stunning 36th-minute free-kick put the English club through to a final four meeting with Spanish side Valencia.
However, coach Unai Emery warned the Gunners to expect a strong response in the second leg in Naples on April 18.
The Gunners have won just five Premier League games on their travels all season, losing 1-0 at Everton last weekend to damage their chances of securing a top-four finish.
Unai Emery's team will host Napoli, who are currently second in Serie A, at the Emirates Stadium in the first leg on April 11.
The Gunners overcame a 3-1 deficit from the first leg to advance to the quarter-finals after a 3-0 win over Rennes.