Manchester United went down to defeat in their opening Europa League group game on Thursday, while Premier League rivals Southampton won and Irish champions Dundalk claimed an impressive draw in the Netherlands.

Below is the best of the action on match day one:
                  
Feyenoord sink United         
         
Jose Mourinho's reluctant return to the Europa League ended in embarrassment as Tonny Vilhena fired Feyenoord to a 1-0 win over Manchester United in their Group A opener in Rotterdam. 

Mourinho sent out a much-changed line-up that could not prevent United slipping to a second consecutive defeat after their painful loss to bitter rivals Manchester City in the Premier League. With only David de Gea, Paul Pogba and Eric Bailly retained from the side beaten by City, it was little surprise to see United deliver a disjointed performance. 

Giovanni van Bronckhorst's team had swept to the top of the Dutch league with five successive victories and they made their lethargic opponents pay when they got the only goal with 11 minutes left. 

Exposed down the right flank by Nicolai Jorgensen's run that beat the offside trap, United's defenders were noticeable by their absence when the unmarked Vilhena swept home from just inside the penalty area and the De Kuip arena exploded. 

United next host Zorya Luhansk, who drew 1-1 at home to Fenerbahce in Ukraine.
                  
Austin stars for Saints     
             
Claude Puel got his first victory as Southampton manager as the Premier League side eased to a 3-0 home victory over Sparta Prague at St Mary's Stadium in Group K.

The Frenchman was left fuming at the weekend when Southampton lost to a harsh injury-time penalty at Arsenal. The boot was on the other foot this time when Costa was harshly adjudged to have handled the ball in the box when it struck his hand. Charlie Austin tucked away the spot-kick after just five minutes and then the striker headed in from a delicious outside-of-the boot cross from Cuco Martina to give the Saints a 2-0 half-time lead.
 
Southampton easily held on in a drab second half and substitute Jay Rodriguez -- on for Austin -- stabbed home in injury time to seal a comfortable night's work.
                  
Dundalk produce more heroics 
                 
Manchester United may have lost in the Netherlands, but Irish champions Dundalk came away with a 1-1 draw from their trip to AZ Alkmaar. 

They looked to be heading for a defeat at the AFAS Stadion after Stijn Wuytens bravely headed AZ into a 61st-minute lead. Wuytens took a punch in the face from Dundalk goalkeeper Gary Rogers as he attacked the ball and needed lengthy treatment before being taken off. There looked to be no way back for Dundalk after captain Stephen O'Donnell was sent off for a second yellow, but substitute Ciaran Kilduff netted the equaliser with a minute to go in their Group D opener. It was a fine result for Stephen Kenny's side, who lost to Legia Warsaw in the Champions League play-offs.                  

Zenit's stunning comeback  
                
The performance of the night came in the other game in the group as former UEFA Cup winners Zenit St Petersburg stormed back from three goals down with less than a quarter of an hour remaining to beat Maccabi 4-3. 

The hosts had appeared to be on easy street as two goals by Haris Medunjanin either side of a Vidar Orn Kjartansson header had them 3-0 in front. But Russian international Alexander Kokorin pulled one back on 77 minutes before Eli Dasa was red-carded for Maccabi. Substitute Mauricio further reduced the deficit and Giuliano equalised on 86 minutes, leaving plenty of time for the Montenegrin Luka Djordjevic to score the winner in injury time with a diving header.
                  
Dream start for Sassuolo   
               
While Inter Milan were beaten at home by Hapoel and both Roma and Fiorentina drew on the road, it was a great night for another Italian side. 

Sassuolo, appearing in Europe for the first time, started their Group F campaign with a rousing 3-0 home win against 2012 Europa League runners-up Athletic Bilbao. Teenage Spaniard Pol Lirola put Sassuolo ahead on the hour mark and they did not look back, Gregoire Defrel making it two on 75 minutes before Matteo Politano sealed the win.

Europa League group stage results on Thursday:​

Group A
At Rotterdam, Netherlands
Feyenoord (NED) 1 (Vilhena 79) Manchester United (ENG) 0 
                  
At Odessa, Ukraine
Zorya Luhansk (UKR) 1 (Grechyshkin 52) Fenerbahce (TUR) 1 (Kjaer 90+5)
                  
Group B
At Bern
BSC Young Boys (SUI) 0 Olympiakos (GRE) 1 (Cambiasso 42) 
                  
At Nicosia
APOEL (CYP) 2 (Vinicius 75, De Camargo 87) Astana (KAZ) 1 (Maksimovic 45+1)
                  
Group C
At Mainz, Germany
FSV Mainz 05 (GER) 1 (Bungert 57) Saint-Etienne (FRA) 1 (Beric 88) 
                  
At Brussels
Anderlecht (BEL) 3 (Teodorczyk 14, Rafael 41-og, Capel 77) Qabala (AZE) 1 (Dabo 20)
                  
Group D
At Alkmaar, Netherlands
AZ Alkmaar (NED) 1 (Stijn Wuytens 61) Dundalk (IRL) 1 (Kilduff 89)
                  
                  
Group E
At Bucharest
Astra Giurgiu (ROU) 2 (Alibec 18, Sapunaru 74) Austria Vienna (AUT) 3 (Holzhauser 16-pen, Friesenbichler 33, Alexander Gruenwald 58)
                  
At Plzen, Czech Republic
Viktoria Plzen (CZE) 1 (Bakos 11) Roma (ITA) 1 (Perotti 4-pen)
                  
Group F
At Reggio Emilia, Italy
Sassuolo (ITA) 3 (Lirola 60, Defrel 75, Politano 82) Athletic Bilbao (ESP) 0
                  
At Vienna
Rapid Vienna (AUT) 3 (Schwab 51, Joelinton 59, Colley 60-og) Genk (BEL) 2 (Bailey 29, 90-pen)
                  
Group G
At Athens
Panathinaikos (GRE) 1 (Berg 5) Ajax (NED) 2 (Traore 34, Riedewald 67) 
                  
At Liege, Belgium
Standard Liege (BEL) 1 (Dossevi 3) Celta Vigo (ESP) 1 (Rossi 13)
                  
Group H
At Konya, Turkey
Konyaspor (TUR) 0 Shakhtar Donetsk (UKR) 1 (Ferreyra 76)
                  
At Braga, Portugal
Sporting Braga (ESP) 1 (Andre Pinto 24) Gent (BEL) 1 (Milicevic 6) 
                  
Group I
At Salzburg, Austria
FC Salzburg (AUT) 0 FK Krasnodar (RUS) 1 (Joaozinho 37)
                  
At Nice, France
Nice (FRA) 0 Schalke (GER) 1 (Baba Rahman 75)
                  
Group J
At Baku
Qarabag (AZE) 2 (Michel 7, Sadygov 90+4) Liberec (CZE) 2 (Sykora 1, Baros 68)
                  
At Thessaloniki, Greece
PAOK (GRE) 0 Fiorentina (ITA) 0
                  
Group K
At Southampton, England
Southampton (ENG) 3 (Austin 5-pen, 27, Rodriguez 90+2) Sparta Prague (CZE) 0
                  
Group L
At Ankara
Osmanlispor (TUR) 2 (Diabate 64-pen, Umar 74) Steaua Bucharest (ROU) 0
                  
At Vila-real, Spain
Villarreal (ESP) 2 (Pato 28, Jonathan dos Santos 45+1) FC Zurich (SUI) 1 (Sadiku 2)