West Ham manager Sam Allardyce lamented his side's missed opportunities after a 3-1 home defeat to Arsenal on Boxing Day.
The hosts took the lead a minute after the break when Carlton Cole tapped home after Wojciech Szczesny parried Kevin Nolan's drive, but West Ham then missed three gilt-edged chances to double the advantage in the next 10 minutes.
Szczesny denied Matt Jarvis when the winger was through on goal, before Joey O'Brien headed Mohamed Diame's cross wide and Cole stabbed Razvan Rat's bouncing delivery off target.
They were made to pay for their wastefulness as Theo Walcott scored twice in three minutes midway through the half to turn the result around, before substitute Lukas Podolski fired in a third 11 minutes from time as West Ham dropped to second from bottom in the Premier League table.
After the match, Allardyce claimed his side had missed a glorious opportunity to claim a vital three points.
"We let it slip through our fingers today," he said.
"We had three golden chances after we scored and we've paid the price because what Arsenal do is take more and more chances.
"It was either going to be us getting the second or they'd score and that's exactly what happened sadly.
"It was a great opportunity to beat a top of the league team and unfortunately we didn't take it and paid the price."
West Ham now face West Brom at home on Saturday before a trip to Fulham on New Year's Day, and Allardyce is in no doubt as to the enormity of those fixtures.
"Our big games are West Brom and Fulham in the next two games," he said.
"It's about performing like that against those clubs which gives you a chance of winning the game.
"We've got to believe we will convert the chances as we did in the home game against Fulham.
"West Brom is becoming a must win game so we've got to go out without being over anxious or over ambitious because if we start leaving back doors open and conceding too many goals we're going to have to score more."
|Barcelona announce record revenues for 2015-16|
|Moyes enjoys Sunderland win as Palace beat Colchester|
|Stoke complete Allen signing|
|Roma coach Spalletti warns suitors off Manolas|
|Cresswell out for up to four months with knee injury|
|Burnley fan banned by club for racist abuse|
|Dad won´t let me play at the Olympics - Larsson Sr pulls rank|
|Kostic joins Hamburg on five-year deal|
|Tevez: I´d turn down Chelsea and Napoli to stay at Boca|
|Mayoral inspired by Benzema for Wolfsburg stint|
|Allardyce straight into competitive action with England|
|Liverpool, Sevilla fined for Europa League final incidents|
|Barcelona seal Guillemenot signing as part of new Servette deal|
|Niersbach handed one-year ban over World Cup corruption|
|Chelsea and Everton ´still interested´ as Koulibaly eyes Napoli exit|
|´Still working hard´ - Balotelli trains with Liverpool kids|
|Winter breaks, long-ball football and the World Cup: Allardyce in his own words|
|Inter warn Napoli Icardi is not for sale|
|Zanetti wants Simeone back at Inter|
|Stoke snap up Sobhi|
|PSG tougher under Emery - Lucas Moura|
|Totti not ready for retirement - Pallotta|
|Confident Allardyce reveals plan for England success|
|Pochettino to discard three Tottenham players|
|Allardyce: Rooney must wait for captaincy decision|
|Aubameyang: I will only leave Dortmund for Real Madrid|
|Allegri silences questions on Pogba|
|Bruce stands by decision to quit Hull City|
|Pochettino: Not the right time for Argentina job|
|Inter yet to approach De Boer with Mancini exit rumoured|
|Ancelotti trusts me more than Guardiola - Ribery|
|Wijnaldum rejected Everton for Klopp|
|Pre-season Manchester derby cancelled|
|Coutinho excited by ´fast´ Liverpool recruits|
|Cristiano Ronaldo and Conor McGregor step into the ring together|
|Mancini coy on reports linking Icardi to Napoli|
|Nolito reveals why he chose Man City over Barcelona|
|Inter 1 Paris Saint-Germain 3: Icardi absence in defeat fuels Napoli talk|
|MLS Review: Wright-Phillips double inspires Red Bulls to New York derby rout|
|James seeks more game time at Madrid|
|Rooney: I want to be a manager|
|Mignolet welcomes Karius challenge in Liverpool number one battle|
|Batshuayi buoyed by winning vibes at Chelsea|
|Moyes and Sunderland players diverted after plane fault|
|´Loved´ Varane targets long Madrid stay|
|Kostic set for Hamburg medical|
|Leicester crying over Kante sale - Ranieri|
|Schurrle the perfect Mkhitaryan replacement - Tuchel|
|West Ham face anxious wait on Cresswell injury|
|Mourinho will accept criticism from United legends|
|Bertolacci desperate for fresh start after underwhelming first season at Milan|
|Hoops hand Toure one-year deal|
|Origi ready to fight for Liverpool spot|
|Emery wants PSG stay for ´fantastic´ Matuidi|
|No Barcelona offer for Vietto - Cerezo|
|Burnley apologise for racist abuse from supporter|
|Guardiola will not rush Kompany comeback|
|Of course I´ll shake Guardiola´s hand, snaps riled Mourinho|
|Watzke: No more signings for Dortmund|
|Roma expect Manolas to snub Premier League move|
|Adriano set to leave Barcelona for Besiktas|
|Manchester United in worst possible situation - Mourinho|
|Sporting would have to sell stadium to afford Van Persie - Jesus|
|Jonas´ agent confirms Barcelona approach|
|No problem with Mourinho, insists Guardiola ahead of derby in China|
|Toronto´s hat-trick hero Giovinco: I´m back|
|Drogba revels in ´special night´, dedicates hat-trick to family|
|MLS Review: Hat-tricks for Drogba and Giovinco as stars shine|
|Whelan backs Liverpool for top-four finish|
|Pellegrini still waiting for right offer|
|Ronaldo deserves to win Ballon d´Or - Vazquez|
|Phelan wants Hull job|
|Alaba saddened by Gotze exit|
|Morgan: Vardy right to re-sign|
|Maradona ´hurting´ as Higuain closes on Juventus move|