Zaha scored the opener with a fine volley early in the first half with Townsend securing the win six minutes from time after winning the ball back on the edge of his area, running 80 yards and hammering a low shot past Ben Foster. It was the ideal embodiment of Palace’s best performance of the season.
An even first half was low on clear-cut chances, not least due to obdurate defensive work in both areas. Whilst Gareth McAuley was a reliable presence in the Albion area his fine display was put into the shade by the outstanding Sakho.
Liverpool’s best defender could be the difference between Palace playing next season in the Premier League or the Championship if he continues to put in performances like that at the Hawthorns.
Even when West Brom were at their best they couldn’t find a way past the Frenchman, whose diving header denied Salomon Rondon what seemed to be a certain goal after Allan Nyom’s teasing delivery from the left on 16 minutes.
Soon after Christian Benteke was handed the best chance of the half. After smartly finding space from a corner as West Brom’s defender tracked Sakho he headed low and hard at goal, only to find Chris Brunt waiting on the post to deny him.
Neither side were able to carve open another chance to match that in a half with only six shots on goal, though seven minutes before the interval West Brom were convinced they had a penalty when Rondon barrelled his way between Joel Ward and Yohan Cabaye.
On initial viewing the Venezuelan striker seemed to have been denied a cast iron penalty as he tumbled on his way into the area but referee Mike Jones was vindicated as replays showed that Rondon had gone down far too easily under Cabaye’s attention.
Palace began the second period much the better side and got their reward after 10 minutes. Having provided his first assist of the season last week Yohan Cabaye delivered an impeccable crossfield ball from just inside the West Brom half for Zaha, who chested down before slamming a low volley past Ben Foster.
Zaha was rampant and nearly forced a second soon after, driving through the Albion defence. Foster was out to parry but Jason Puncheon should have scored from the rebound, deflected wide.
An injury to Patrick van Aanholt threatened to derail Palace’s momentum and Hennessey’s fumbling of a Brunt cross added to the nerves.
But after surviving five minutes of pressure Palace were back to their defiant best, Sakho typifying their defensive improvements as he managed to tackle both the referee and Livermore to win the ball in midfield.
Townsend, whose defensive endeavour was notably improved, should have won it when one-on-one with Foster he failed to find the corner but made amends soon after, stealing the ball from Jonathan Leko before releasing the after-burners on his way to an exceptional winner.