Albion had been chasing a seventh successive home win but found clear-cut chances hard to come by against the Premier League visitors.

Palace manager Roy Hodgson, who was in charge at The Hawthorns between February 2011 and May 2012 before leaving to take charge of England, made eight changes to his starting line-up with Albion boss Darren Moore making 10.

Hodgson could not have wished for a better start as Townsend shocked Albion with a spectacular piece of finishing.

Albion paid the full price for not closing down Townsend and letting him run with the ball. Townsend let fly and his drive gave Albion goalkeeper Boaz Myhill no chance.

Despite the shock of falling behind, Albion almost produced an immediate response only for James Morrison to pull his shot from 25 yards narrowly wide of Vicente Guaita’s near post.

But Palace looked by far the more threatening side in the opening exchanges and Jeffrey Schlupp should have done better when he placed a 16th-minute header straight at Myhill from eight yards before Van Aanholt had his shot saved seconds later.

Alexander Sorloth then twice tested Myhill with headers – either side of Max Meyer seeing his shot saved – as Palace made a determined bid to increase their advantage.

Having managed to ride out the storm, Albion were finally able to mount a worthwhile attack of their own four minutes before half-time, when only the outstretched hand of Guaita denied them an equaliser as he saved from Morrison after good work from Wes Hoolahan.

Palace were again frustrated on the stroke of half-time when Townsend saw his delicate shot cleared off the line by Ahmed Hegazi.

That frustration continued five minutes into the second half when Schlupp’s rising drive was turned away by Myhill before Meyer had a 57th-minute close-range drive blocked in a crowded goalmouth.

Palace finally got their reward when Van Aanholt made an adventurous run forward and got a fortunate ricochet on the edge of the area after cutting in from the wing before rifling a right-foot drive past Myhill.

Townsend then set the seal on a clinical Palace display when he cut inside Hoolahan and Sam Field before beating Myhill with a thunderous angled drive.

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