The likes of Leicester, Napoli, West Ham, Real Betis, Lyon, Leverkusen, Monaco, and many others kick off their European campaign on Thursday.

The UEFA Europa League has finally made its return! After a near four-month break, Europe's second-tier club competition is back in full swing again, with the 2021/22 season kicking off on Wednesday, September 15 with the Spartak Moskva vs Legia Warszawa showdown.

The Polish outfit won that encounter 1-0, with Lirim Kastrati netting the first goal of the 2021/22 Europa League campaign courtesy of a stoppage-time effort to break the hearts of their Russian opposition.

The rest of the 15 games will be staged on Thursday as typical, with eight of the fixtures kicking off at 12:45 p.m. ET while the remaining seven will get underway at 3 p.m. ET. The likes of Real Betis, Fenerbahce, Napoli, Celtic, Leicester, Monaco, Real Sociedad, Lyon, West Ham and many others will commence their battle to lift this European crown.

Who will be facing off on Matchday 1 of the new Europa League term? What are the standout fixtures of the opening round? Here's everything you need to know about Thursday's clashes.

What are the groups for the 2021/22 UEFA Europa League season?

 2021/22, UEFA Europa League. Europa League Draw, Napoli, Leicester, West Ham, Real Betis, Bayer Leverkusen, Monaco, Rangers, Celtic, Galatasaray

Top games to watch on Matchday 1 of the 2021/22 UEFA Europa League season

Galatasaray vs Lazio: The Turkish giants were handed a heartbreak in the UEFA Champions League playoffs as PSV handed Galatasaray a defeat, thus relegating them to the UEFA Europa League. The Super Lig giants, who have begun the Turkish top-flight well, were accustomed to UCL action but will now have to make do with UEFA's second-tier club competition.

Fatih Terim's side will be in for a tough test. Their first opponent will be Lazio, who recently lost 2-0 to AC Milan in Serie A. Regardless, the Italian side, under the helm of newly-appointed Maurizio Sarri, will look to prove themselves after enduring a disappointing end to the 2020/21 season. Do not miss this fixture.

Real Betis vs Celtic: Not only have these two teams never faced before, but Real Betis have also never clashed with a Scottish club. The Spanish side, who won their first three points of the Spanish top-flight campaign on Monday, will look to kick off their European campaign with a victory. This is crucial as Bayer Leverkusen and Ferencvaros await them in Group G.

Celtic, meanwhile, look to re-establish themselves as a formidable team after losing the Scottish Premiership title to bitter rivals Rangers. Furthermore, the Hoops also crashed out of the UEL in the first round last season, finishing bottom of their group, and will thus seek redemption. 

Leicester City vs Napoli: These two teams shared a lot of parallels last season. Both finished in fifth, only just narrowly missing out on a UEFA Champions League berth, and were dumped out in the 2020/21 Europa League campaign in the round of 32 despite being one of the favorites for the title.

However, where they differ in is form. The Italian giants head into this clash on the back of an impressive 2-1 comeback victory over Juventus over the weekend, with goals from Matteo Politano and Kalidou Koulibaly maintaining their perfect start to the campaign. The Foxes, on the other hand, enter this tie on the back of a 1-0 loss at home to Man City. Brendan Rodgers' men have endured a mixed start to the campaign, having lost two and won two of their opening four fixtures. Can they bounce back against Insigne and Co? Tune in to find out the answer.

Who's in and who's out?

Here are the list of players ruled out for the upcoming round from the UEFA Europa League's top clubs:

West Ham: Winston Reid

Real Betis: Marc Bartra, Youssouf Sabaly (doubt), Diego Lainez (doubt)

Celtic: Greg Taylor, Christopher Jullien, Kyogo Furuhashi, James Forrest (all doubts)

Leicester: James Justin, Namplays Mendy, Wesley Fofana

Napoli: Alex Meret, Faouzi Ghoulam, Diego Demme, Stanislav Lobotka, Dries Mertens, Lorenzo Insigne (doubt), Mario Rui (doubt)

Rangers: Ianis Hagi, Nnamdi Ofoborh

Lyon: Leo Dubois, Jeff Reine-Adelaide, Marcelo, Lucas Paqueta, Bruno Guimaraes, Tinotenda Kadewere

Full list of games for Matchday 1 of the 2021/22 UEFA Europa League season