A dejected Arsene Wenger felt a more clinical Arsenal might have already booked a place in the Europa League final after a frustrating 1-1 semi-final first leg draw against Atletico Madrid.
The visitors were reduced to 10 men at Emirates Stadium as Sime Vrsaljko astonishingly collected two bookings inside the opening 10 minutes.
Alexandre Lacazette and Danny Welbeck both spurned chances to put Arsenal ahead before the break but the former made it seven goals in his past seven matches across all competitions with an expertly directed header from Jack Wilshere's 61st-minute cross.
However, Antoine Griezmann pounced on a slip from Laurent Koscielny to poach a vital away goal for Diego Simeone's side and end Wenger's final European home game at the helm on a sour note.
"Looking at the performance we had and the way the game went it was the worst possible result," he told BT Sport.
"We have to go there in a positive mood and qualify over there. We have to recover from a disappointment and prepare for the next one.
"It felt like an opportunity missed. We could already be qualified but it didn't happen. Their goalkeeper made many saves and you could see that they have the quality up front to take advantage
"We knew if we did not score the second one it was important we did not concede."
1 - Arsenal have lost just one of their eight semi-final first legs in European competition (W4 D3), while they’ve progressed from the tie on every previous occasion they’ve avoided a first leg defeat. Hope. pic.twitter.com/V95yHcKbHc— OptaJoe (@OptaJoe) April 26, 2018
Atleti's defensive obduracy was on full display as they battled with reduced numbers and LaLiga's second-placed team have not conceded in any of the past 11 matches at the Wanda Metropolitano.
Nevertheless, Wenger is refusing to be daunted by the task awaiting his team next week.
"You don't look at the statistics, you look at your performance and we know we can score anywhere," he added.
"First recover, because the players have given a lot, and then see what we can do over there.
"We have to go there with absolute belief to do it."
|What bothers me is that he has time to even do that – LeBron responds to Trump tweet|
|Cowboys most valuable NFL team for 12th successive year|
|Mkhitaryan aiming for glory with Europa specialist Emery|
|Sarri: Pedro´s injury is not too serious|
|This Week in U.S. Sports: Drama in Minnesota, a Judge returns and tragedy in Iowa|
|Tottenham will overcome rough patch – Lamela|
|Torreira impresses for Arsenal but leaves with knock|
|Gattuso urges Higuain to be less predictable with his movement|
|Steelers´ Brown: ´Obviously I don´t want to be traded´|
|Woods, Fowler share Tour Championship lead|
|LeBron James backs Serena Williams after US Open controversy|
|Thiem into St Petersburg quarters, but retiring Youzhny bows out|
|Wigan clinch home semi-final with win over Huddersfield|
|Can apologises following sexism accusations|
|De Bruyne expects to be back for Manchester derby|
|Celtic 1 Rosenborg 0: Griffiths late show lifts Hoops|
|Woods eagles 18 to make 65 at Tour Championship|
|Arsenal 4 Vorskla 2: Aubameyang at the double in entertaining triumph|
|Dudelange 0 AC Milan 1: Deflected Higuain goal spares Gattuso´s blushes|
|Birthday boy Rashid inspires Afghanistan to Asia Cup win|
|Sarri feeling sorry for ´unlucky´ Morata|
|Ryder Cup pick Garcia shoots 66 at Portugal Masters|
|Ronaldo, Zidane, Cantona and the most infamous red cards|
|Villarreal 2 Rangers 2: Arfield and Lafferty steal point for Gerrard´s men|
|PAOK 0 Chelsea 1: Willian strikes as Morata misfires|
|Rain delays Ostapenko in Seoul, Wang books Guangzhou semi|
|Pochettino backs Kane to end goal drought|
|We figured it out - 76ers´ Markelle Fultz rebuilds jump shot|
|Joshua: Povetkin my second-toughest fight|
|Relaxed Pochettino not pushing panic button|
|Why Manchester City fans must fix their relationship with the Champions League|
|Majestic Giorgi ends Wozniacki´s reign in Tokyo|
|Pochettino unwilling to risk Alli fitness|
|Bigger Champions League tests to come, warns Pogba|
|Eight for 10! - Nadeem spins his way to world-record figures|
|A 4-1 lead cut to 3-2 by VAR, but Quakes have no complaints after Atlanta defeat|
|UEFA opens disciplinary proceedings against Ronaldo|
|Joshua v Povetkin: Recapping AJ´s previous world title defences|
|Players told to ink twice over showing tattoos at Rugby World Cup in Japan|
|Mariano targeting Spain call-up after goalscoring Madrid return|
|Pandya, Axar and Thakur out of Asia Cup|
|England omit Cipriani, Tuilagi and Ashton called up|
|Can reacts to Ronaldo´s red card: We are not women|
|One Year to Go: Five Rugby World Cup debutants set to shine|
|Shy Osaka not comfortable with new-found fame|
|Belgium and World Cup winners France make FIFA rankings history|
|Ronaldo wanted to impress - Bernardeschi sympathises after Juve superstar´s red|
|Van Dijk warns Liverpool: Believe we can win trophies or stay home|
|Menezes complains of anti-Brazilian conspiracy after Dede´s VAR red|
|Diamondbacks rout Cubs to remain in postseason picture|
|Modric embraces Ballon d´Or chants as Di Francesco backs Madrid star for award|
|MLS Review: Martinez helps Atlanta stage comeback amid VAR controversy|
|Kerevi recommits to Wallabies, Reds|
|Lyon to ban fan for life after footage of Nazi salute emerges|
|Milan must respect opponents – Gattuso not underestimating Dudelange|
|Copa Libertadores Review: Zarate leads Boca, River draw|
|Mourinho: Dalot can play at Man United for more than 10 years|
|Johnson hoping to erase East Lake demons|
|´No question´ Fitzgerald faces Bears, says Cardinals´ Wilks|
|Rodgers says roughing the passer penalties are ´going the wrong direction´|
|Ravens fined $200,000 for violating communication policy|
|LeBron James set to star in ´Space Jam´ sequel|
|Ronaldo red card ´absurd´, says Pjanic|
|Kovac hails ´special´ Sanches after Bayern goal|
|Marcelino: Tearful Ronaldo said he did nothing wrong|
|Fernandinho takes blame for Man City´s Lyon loss|
|Lovren denies any wrongdoing after perjury charge|
|Plzen boss Vrba slams late mistakes|
|I almost scored as many as Messi - Tagliafico the unlikely hero for Ajax|
|Ronaldo deserves Ballon d´Or not Modric, says Casemiro|