Peterborough United are into the hat for the fifth round draw of the Emirates FA Cup after twice coming from behind to earn a 2-2 draw at the Hawthorns.
Shaquile Coulthirst bagged his first goal in Posh colours with a composed finish to cancel out one-time Posh loanee Saido Berahino's opener in the first period.
Jon Taylor slipped to allow Berahino to put the Baggies back in front in the final 10 minutes, but the same Posh player popped up with a fine volley to earn a share of the spoils and a replay at the ABAX Stadium.
Irishman James McClean was the early threat for the Baggies, two forceful runs down the left created panic, but his crosses were poor and were cleared.
The deadlock was broken on 14 minutes as Beautyman gave away possession in midfield and the ball was worked to one-time Posh loanee Saido BERAHINO who fired low past Alnwick from 20-yards.
On 20 minutes, Oztumer picked out Coulthirst on the edge of the box, he took a touch and fired just past the far upright with Myhill at full stretch.
Pocognoli fired over from 35-yards before moments later Alnwick was fortunate to pounce on a loose ball after taking a heavy touch following a Smith back-pass.
On 33 minutes, Almeida Santos was dispossessed by Mclean who had a clear run on goal, but goalkeeper Ben Alnwick produced a superb stop dashing from his line.
McClean squirmed a volley just past the post after a flick into the air from Lambert on 36 minutes.
On the stroke of half-time, a sharp turn from Angol saw him create space 25-yards from goal, but his low shot went wide of the target.
Posh made a double change at the break with Martin Samuelsen and Jon Taylor replacing Wilson and Beautyman. Posh were much brighter as a result at the start of the second half with Taylor's pace causing problems.
Bostwick fired into the wall with a free-kick after a neat passage of possession involving Oztumer and Angol. Marcus Maddison replaced Oztumer on the hour mark.
Mclean was booked for hacking at Forrester on 66 minutes with Victor Anichebe introduced as a substitute moments later for Sessegnon.
The hosts caught Posh on the counter attack on 70 minutes with Rondon picking out Gardner, but his left-foot shot went over the bar.
Coulthirst fed Smith moments later onrushing from left back, but his low shot was straight at goalkeeper Myhill who made a routine stop.
Maddison tested Myhill from long-range on 74 minutes, but the keeper was up to the challenge and made a comfortable save. McClean cut inside onto his left-foot on 77 minutes, but his shot went well wide of the far post.
Posh found the equaliser on 78 minutes, a superb raking pass from Bostwick picked out COULTHIRST and he cushioned a side-footed effort past Myill and into the back of the net to send the 4,000+ Posh fans behind the goal wild with excitement.
On 84 minutes, the Baggies got themselves back in front as a cross from the right was not dealt with, Taylor slipped and BERAHINO took advantage, firing low into the far corner.
It was instant redemption for TAYLOR though, as moments later he collected a knock down from Santos and rifled a superb volley into the far corner. McAuley flicked a corner kick over the bar from a corner kick on 88 minutes.
In stoppage time, Maddison floated a free-kick over the bar after some superb skill from Samuelsen had won the set-piece.
West Brom: Myhill, Yacob, Evans, Gardner, McClean, Lambert (sub Rondon 62min), Berahino, McAuley, Dawson, Sessegnon (sub Anichibe 67min). Unused subs: Rose, Olsson, Chester, Gamboa, Leko.
Posh: Alnwick, Smith, Wilson (sub Samuelsen 46min), Almeida Santos, Bostwick, Baldwin, Forrester, Beautyman (sub Taylor 46min), Oztumer (sub Maddison 60min), Angol, Coulthirst. Unused subs: Henry, Fox, Coulibaly, Da Silva Lopes.
Half-time: West Bromwich Albion 1-0 Peterborough United
Full-time: West Bromwich Albion 2-2 Peterborough United