Leaders West Brom rescued a point against Barnsley to remain top of the Sky Bet Championship after coming from 2-0 down to draw 2-2 at the Hawthorns.
West Brom were left shellshocked after conceding two first-half goals against a determined Tykes side but recovered to make it 16 points from losing positions this season.
Barnsley, seeking their first win since the opening day of the season, went ahead in the 18th minute with the first real attack of the game.
Six minutes later, Barnsley doubled their lead with a move built from the back.
Midfielder Alex Mowatt cut in from the left for Woodrow, who cashed in on the space in front of him by lashing into the far corner.
It was no more than Albion deserved after they were a distant second best in the first 45 minutes.
Normally free-scoring, the only effort they registered near goal was a deflected shot from Grady Diangana that drifted into the side-netting.
But it made little difference as Albion continued to be wasteful in possession and let themselves down with sloppy fouls.
Instead of a revival, it was Barnsley who went desperately close to the next goal.
Cameron McGeehan's looping header hit the bar after Cavare again was the provider from the right flank.
There seemed no way back for West Brom for long periods, with Barnsley blocking them at every turn and leaving two men up front at all times ready to counter-attack.
West Brom were piling on the pressure in the latter stages and Barnsley erected a tireless red wall to keep them at bay, throwing their bodies in the way of everything.
But it was one of their own that ultimately and cruelly let them down.
Diaby glanced Pereira's inswinging corner past his own keeper Brad Collins, before Pereira timed his run perfectly to head home Townsend's whipped-in cross, with the youngster having looked a danger from the moment he came on.
Barnsley had eight players booked as they strained every sinew to earn a share of the spoils.