Harry Maguire struck in the 91st minute to spare Manchester United's blushes as they rescued a 3-3 draw at Porto in the Europa League on Thursday, while Chelsea kickstarted their Conference League campaign with a home win.
Tottenham maintained their 100 percent start in the Europa League at Ferencvaros and Serie A side Roma went down 1-0 in Sweden against Elfsborg.
The beleaguered Erik ten Hag's Man United made a blistering start in Porto with goals from Marcus Rashford and Rasmus Hojlund firing them into a 2-0 lead in the opening 20 minutes.
But Pepe pulled one back for the hosts on 27 minutes before a brace by Samu Omorodion on either side of the break flipped the game on its head.
Bruno Fernandes was given his marching orders for a high boot with nine minutes remaining and United seemed to be heading to a second defeat in a week after losing their skipper to another red card.
But Maguire popped up in injury time to head in from a corner and grab the Manchester club their second draw in two Europa League outings this term and relieve some of the pressure on Ten Hag.
WINNING START FOR CHELSEA
Chelsea marked their first-ever appearance in the Conference League with a 4-2 win over visiting Belgian side Gent.
Manager Enzo Maresca utilised his large squad, naming an entirely different starting XI to the one that played in the league at the weekend.
Renato Veiga headed Chelsea into the lead in the 12th minute, which Pedro Neto then doubled one minute after the interval.
Tsuyoshi Watanabe made it 2-1 in the 50th minute but two goals from Christopher Nkunku and Kiernan Dewsbury-Hall in seven minutes killed off the tie before Omri Gandelman scored a consolation.
A 44th-minute penalty by Michael Baidoo was enough to give Elfsborg a surprise 1-0 win at home to Roma, who sit on one point after two games.
JOHNSON ON FIRE
Earlier, Tottenham ground out a 2-1 win away to Hungary's Ferencvaros in the Europa League.
Goals in both halves from Pape Sarr and Brennan Johnson did the job for spurs despite a late Barnabas Varga strike.
"I'm really happy. It's never easy going away from home in Europe," Spurs manager Ange Postecoglou told TNT sports.
"You saw the atmosphere tonight, there were a lot of things to deal with and also with four teenagers (in the team)."
An inexperienced Spurs side made a slow start and Ferencvaros thought they had taken the lead in the 18th minute through Varga, but VAR ruled that there had been an offside in the build-up.
The Premier League club broke the deadlock in the 23rd minute when Sarr was the only player in the Ferencvaros box to keep his cool.
The home side failed to clear the danger on three occasions, allowing Sarr to pounce and slot home from inside the six-yard box.
As Ferencvaros started to threaten late on, Johnson got his fifth in as many games with a left-footed finish that kissed the post on its way into the back of the net in the 86th minute.
And Spurs needed the two-goal buffer as Varga scored in the 90th minute to set up a nervous finale.
Anderlecht came from behind at La Liga's Real Sociedad to earn a 2-1 win, Lazio hammered Nice 4-1 under the rain in Rome and Ajax drew 1-1 at Slavia Prague.
Latvia's RFS came from two down at home to Galatasaray to snatch a 2-2 draw and Lyon strolled to a 4-1 victory at Rangers.
In the Conference League, Cercle Brugge cruised to a 6-2 victory at home to Swiss club St Gallen as Legia Warsaw surprised Real Betis 1-0 in the Polish capital.
Larne became the first Northern Irish team to play in a UEFA competition proper but succumbed to a 3-0 defeat in Norway against Molde.
The New Saints of Wales also made their debut in the league phase of a European competition away to twice Conference League runners-up Fiorentina where the hosts need two second-half goals to emerge 2-0 winners.