Infotainment Factory: 'Ridiculous' decision mars megastar's return

A controversial penalty decision cost Manchester United dearly in a 1-0 upset home loss against Real Sociedad to open their Europa League campaign.

The harsh penalty was awarded for a handball by defender Lisandro Martinez and upheld by VAR despite replays showing the ball only hitting the defender's arm after bouncing off his knee.

Brais Mendez converted from the spot for Sociedad in the second half at Old Trafford, hitting the bottom corner of David de Gea's goal.

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But despite that bad luck United were poor and felt the wrath of their demanding fans.

Cristiano Ronaldo returned to United's starting line-up after failing to secure a transfer to a Champions League club and having to settle for playing in Europe's second-tier competition for the first time since 2002 with Sporting Lisbon.

Ronaldo had last started in a 4-0 loss to Brentford on August 13 before United chalked up four consecutive victories in the Premier League.

United manager Erik ten Hag had used the Portugal star off the bench during the winning streak.

It was Sociedad's first win over United in European competitions.

Before their opening group stage game, a minute of silence was held to pay respect to Queen Elizabeth II, who died at the age of 96 on Friday (AEST).

"The club recognises her immense contribution to public life, including sport, both here in the United Kingdom, across the Commonwealth, and around the world," United said in a statement.

Elsewhere, Brazilian teenager Marquinhos marked his Arsenal debut by scoring the opening goal and setting up a second in a 2-1 victory over Zurich in their opening group stage match.

Eddie Nketiah scored the winner after Zurich equalised from a penalty awarded due to his foul as Arsenal rebounded from a 3-1 loss to United — their first defeat in the Premier League this season.

The duo of Nketiah and Marquinhos were involved in the decisive moments of Arsenal's victory while United States goalkeeper Matt Turner made his debut for the Gunners following his summer transfer from the New England Revolution.

Nketiah found the back of the net with a header in the second half that went in between the legs of Zurich goalkeeper Yanick Brecher off a cross from Marquinhos, who joined Arsenal this summer from Sao Paulo.

In the London club's return to European football after a one year absence, the 19-year-old Marquinhos met a cross from Nketiah from the left to side foot into the top corner and finish off a fluent counter attack 16 minutes into the game.

Despite Arsenal's dominance, the hosts equalised a minute before halftime after Mirlind Kryeziu sent Turner the wrong way from the spot.

Lazio opened its campaign with a 4-2 victory over Feyenoord but fellow Italian club Roma lost 2-1 at Ludogorets in Bulgaria.

In the third-tier Europa Conference League, West Ham rallied in the second half to beat Romania's FCSB 3-1 in London.

Elsewhere, Villarreal beat Lech Poznan 4-3 while Fiorentina was held 1-1 at home by Latvian champion RFS.

The start of a match between Nice and Cologne in the ECL was delayed because of fights among supporters in the stands at Allianz Riviera stadium.

Kick-off was pushed back by 55 minutes. The match ended in a 1-1 draw.

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