West Brom visit is must win for West Ham - Sam Allardyce

West Ham boss Sam Allardyce feels it is critical for his side's survival bid that they beat West Brom on Saturday.

The Hammers slipped into the Premier League relegation zone after losing 3-1 to Arsenal and next host the Baggies, who sit three points above them.

"West Brom is becoming a must win, without being over-anxious or over-adventurous," said Allardyce.

"You can always lose to Arsenal, but our big games are West Brom and Fulham in the next two."

Arsenal dominated the first half at Upton Park but could not capitalise and West Ham opened the scoring just after the break through Carlton Cole.

West Ham woe

Since beating Cardiff on the opening day of the Premier League season, West Ham have managed only two top-flight wins in 17 games

But they wasted three glorious chances to double their advantage and Arsenal equalised through a Theo Walcott strike. The Arsenal forward then headed the visitors in front before Lukas Podolski lashed home a third.

"We let it slip through our fingers," said Allardyce. "Three golden chances for 2-0 through Matt Jarvis, Joey O'Brien and Carlton Cole.

"We had a great opportunity to beat the top of the league team, unfortunately we didn't take that and we paid the price."

Results elsewhere meant West Ham fell from 17th and a point outside the bottom three to 19th and two points inside it.

They have won only one of their last 11 league games and after the visit of managerless West Brom comes a trip to Fulham on 1 January.

Since causing an upset at Tottenham on 6 October, West Ham's only victories have come over Burnley and Spurs in the Capital One Cup either side of a 3-0 win against Fulham at Upton Park in the Premier League.

"We've got to make sure we play like we did against Arsenal - and like at Tottenham in the cup - against West Brom and Fulham," Allardyce continued.

"When we've had the opportunity recently we haven't done that, apart from against Fulham. Against Sunderland, Aston Villa, Crystal Palace and Norwich we didn't do it. That's our key let down this season.

"If we can perform like this against the clubs around us, we will create chances and we've got to believe we will convert them."

Allardyce suffered his latest injury setback when James Collins was forced off with a calf problem in the 38th minute.

"On top of all the other injuries, it's a great concern for me," he added. "The squad is down to 15 or 16 players so I may have to step some of youngsters in. It's making the situation more difficult to get out of."