West Ham maintained their hopes of automatic promotion from the Championship in emphatic style, as they swept Barnsley aside to seal to a club record 12th away win of the season.
Three goals up inside the opening 35 minutes, the visitors moved within three points of second-placed Southampton. Sam Allardyce had suggested that anything other than victory would end his side's hopes of finishing in the top two, but it was soon clear they would avoid any such pitfalls with consummate ease.
"It was a measured, controlled performance with a lot of quality," the West Ham manager insisted. "It's a terrific result and well deserved. We've broken a club record which I'm really pleased about for the players and our fans. We've given them something to cheer about all season away from home and it's just a shame we can't transmit that into our home form. Automatic promotion is still in sight."
Kevin Nolan stabbed home his 11th goal of the season from close range as Nicky Maynard flicked on Matt Taylors in-swinging corner after seven minutes for the Hammers' first.
Maynard's second goal for the club since a £1.5m move from Bristol City in January doubled the advantage on 23 minutes, the forward firing the ball into the bottom corner from 20-yards to round-off a free-flowing 10-pass move. Mark Noble chipped the third after a mistake from goalkeeper David Button presented the midfielder with the ball on the corner of the Barnsley area.
Ricardo Vaz Te, who remains Barnsley's top scorer on 12 despite leaving for Upton Park in January, volleyed his fourth goal in five games from close range 10 minutes after the break.
Barnsley (4-4-2) Button; Wiseman, Foster, McNulty, Golbourne (L Collins 61); Cotterill, Dawson, Smith (Perkins 64), Higginbotham; Davies (O'Brien 64), Gray. Substitutes not used: Lidakevicius, Tonge.
West Ham United (4-4-2) Green; Demel (D Collins, 59), Tomkins, Reid, McCartney; O'Neil (Lansbury, 70), Nolan, Noble (Diop, 80), Taylor; Vaz Te, Maynard. Substitutes not used: Baldock, Cole.
Referee: T Bates (Staffordshire).