West Ham's Europa Conference League quarter-final with Gent is finely poised after the first leg ended in a 1-1 draw on Thursday night.
Danny Ings' first ever European goal and third since joining West Ham gave the visitors the lead on the stroke of half-time (45+3) but they had to withstand a late onslaught at the Ghelamco Arena.
While the Hammers, seeking to break a 43-year trophy drought, saw their 100 per cent record in Europe this season ended in the second period, David Moyes will feel confident of completing the job back on home soil.
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Gent had won 10 of their previous 15 home games, and Alessio Castro-Montes was involved in the equaliser as he combined with striker Hugo Cuypers, who steadied himself before reversing his shot beyond Alphonse Areola (56).
There was late drama when referee Tasos Sidiropoulos opted to reverse his decision to send off Kamil Piatkowski after a VAR review having initially dismissed him for a challenge on Lucas Paqueta. Replays showed he got the ball.
Gent's Gift Orban and Tarik Tissoudali both missed good chances to take a slender lead into the second leg next Thursday but the draw means it is the Premier League side who will look to make the most of home advantage at the London Stadium.
Moyes told BT Sport: "I'm not really pleased with the result but a draw away from home in Europe you will nearly always take.
"I expected a bit better, nevertheless it gives us a great chance in the second leg. I have to praise Gent as they were very physical."
Job done for West Ham in Belgium
West Ham had won all five of their previous away Europa Conference League games, scoring 12 goals, conceding only two in keeping four clean sheets.
Moyes' side were ponderous, at times, during the opening 45 minutes as Jordan Torunarigha and Joseph Okumu headed presentable opportunities wide, but the visitors came alive in the closing stages.
They were unfortunate not to lead when a mistake from Davy Roef resulted in the Gent goalkeeper spilling the ball into his own net.
Roef's blushes were spared, however, after VAR intervened having seen a handball by Nayef Aguerd during the spillage. It would prove a very short reprieve.
Gent switched off on the stroke of half-time from a throw in. Jarrod Bowen was alert to Vladimir Coufal's quick-thinking as he latched onto the restart to cross for Ings to tap home.
The goal was subject to another VAR check, this time for offside, but the decision went the way of the Hammers to delight the 1,000 visiting fans squashed into the corner at the opposite end.
On his first European appearance since October 2015, Ings had his maiden strike on the continent.
Fourth in the Belgian first division, Gent reached the quarter-finals by beating Qarabag of Azerbaijan and Turkish side Istanbul Basaksehir in the knockout rounds.
Last season the Hammers melted in the cauldron of Eintracht Frankfurt's Deutsche Bank Park, crashing out in the semi-final of the Europa League. Here, they showed maturity to absorb Gent's expected second-half response.
AZ Alkmaar or Anderlecht await the winners of this tie - and the second half was blown wide open when the hosts levelled just 11 minutes after the restart.
West Ham were sloppy and caught ball-watching as Castro-Montes strolled forward and found Cuypers, who had time to steady himself and blast in his sixth goal in his last five games and 25th in all competitions this season.
The momentum was with Gent, who might have completed the turnaround when Castro-Montes dragged his shot wide midway through the second period.
The lively Orban, who scored the fastest hat-trick in European competition at Istanbul Basaksehir in the last round - timed at just three minutes and 25 seconds - sliced another attempt off target.
Paqueta was summoned by Moyes from the bench and the Brazilian showed superb vision to spot the diagonal run of Bowen, whose shot was miscued.
There was still time for Orban to produce a brilliant piece of improvisation in the final 10 minutes as he looked to catch Areola off his line with an overhead kick which looped onto the top of the bar - but West Ham survived with a valiant draw despite the late drama involving Piatkowski.
Moyes: We didn't get the basics right
West Ham boss David Moyes:
"There were a few decisions that didn't go our way tonight which maybe might have done on other nights but it was more to do with us encouraging Gent to put us under pressure.
"We started the game well but then didn't threaten them enough. We conceded a really poor goal and didn't win enough first and second balls. We didn't get enough of the basic things right tonight which was disappointing.
"If we create chances, Danny [Ings] will take them. We didn't create enough tonight, we didn't build well enough and made it difficult for ourselves. We were more liable to score a second on the counter, but it didn't materialise.
"Hopefully we can show them a bit more about how we play when we see them next Thursday."
Gent coach Hein Vanhaezebrouck said: "We could have achieved a better result. There were chances to score more. The goal we conceded was through a lack of concentration.
"London won't be easy but it remains open. We still have the opportunity to get a good result there."
Gent good value for draw - but prize remains in sight for Hammers
Sky Sports' Ben Grounds:
"The dulcet tones of Doris Day played over the Ghelamco Arena's tannoy system at the final whistle. Que Sera Sera. Day may not have had the prospect of a Europa Conference League semi-final in mind but this tie remains firmly in the balance.
"Ings tucked away Bowen's cross on the stroke of half-time - thanks in no small part to a Gent ball boy - to give them the lead in the first leg of the Europa Conference League quarter-final.
"West Ham's defending let them down after the break as they allowed Gent forward Cuypers to equalise, leaving the tie finely poised heading into next week's second leg at the London Stadium.
"There was late drama with the red card wiped out, and so was West Ham's lead. Moyes stood on the touchline as he remonstrated with the fourth official regarding the Piatkowski on Paqueta incident but he will reflect on this as another step in the right direction.
"This was pretty breathless at times and while Moyes might not have been entirely happy with his side's performance, this is far from a bad result away from home in the first leg of a European quarter-final.
"Via a fairly circuitous route, referee Sidiropoulos reached the right decision to ensure Piatkowski isn't suspended for the second leg - in keeping with West Ham's European adventure. Moyes has fallen foul of ball boys on the continent before; he was sent off for kicking a ball at one in their semi-final defeat at Eintracht Frankfurt last season.
"He will have to make do without Angelo Ogbonna when the sides do it all again in a week's time after his first-half booking triggered a one-match ban, but this is a sound scoreline if not a convincing display.
"There were signs of the West Ham of old, but the version that remains locked in a relegation battle reared its head. Still, the chance to seize this rare chance to deliver European silverware at Prague's Fortuna Arena on June 7 hangs in front of them. Whatever will be, will be."
Ings: We knew we had to suffer
West Ham striker Danny Ings told BT Sport:
"We came into the game knowing there would be times where we would have to suffer. The fans here were electric and it was difficult to control the game so I think the draw is a fair result.
"We just didn't find a rhythm, we lost too many second balls and made it difficult for ourselves. We didn't pass the ball enough so not a great performance but we didn't lose the game so there are positives.
"It has been years since I last played in Europe and nice to get a goal but I'm still disappointed with the way we played as a team.
"I think we were all unhappy at half-time, we didn't move the ball well enough. In the last 10 minutes it was difficult so to come away with a draw, there's lots to improve on next week."
What else happened in the Europa Conference League?
Anderlecht boosted their hopes of meeting the winners of that tie in the semi-final as Michael Murillo and Majeed Ashimeru scored in a 2-0 home victory over AZ Alkmaar.
In the same competition Terem Moffi struck twice for Nice in their 2-2 draw against Basel in Switzerland.
Zeki Amdouni put Basel ahead from the penalty spot after 26 minutes but Moffi gave Nice a half-time lead. Amdouni's header 19 minutes from time levelled matter.
Fiorentina ran out comfortable 4-1 winners at Lech Poznan with Arthur Cabral, Nicolas Gonzalez, Giacomo Bonaventura and Jonathan Ikone on target with Kristoffer Velde replying for Poznan.
What's next?
The second leg takes place at the London Stadium on April 20; kick-off 8pm.
Up next for West Ham, they host Premier League leaders Arsenal on Sunday, live on Sky Sports; kick-off 2pm.
Meanwhile, Gent travel to Mechelen, also on Sunday; kick-off 3pm.