Battling Albion came from two goals down to seal a 2-2 draw against Barnsley and secure their longest unbeaten league run at The Hawthorns since 1920.
The Baggies found themselves two goals down after just 24 minutes courtesy of Cauley Woodrow's brace for the Tykes.
Yet Matheus Pereira proved the catalyst for a revival, his inswinging corner headed into his own net by Bambo Diaby, before the Brazilian nodded home an 81st-minute leveller.
It captured a deserved share of the spoils and ensures the Baggies remained undefeated at The Hawthorns in the Sky Bet Championship since February, a run stretching 13 matches - the club's third-longest in history.
Slaven Bilić's resilient Albion, who have lost just once in the league this term and remain top of the table, will be looking to get back to winning ways when Charlton Athletic are the visitors this weekend.
Albion showed one change from Saturday's 1-0 victory at Middlesbrough, Kyle Edwards recalled in place of Filip Krovinović, who dropped to the bench.
The hosts started on the front foot, dominating in the opening 15 minutes, yet it was Barnsley who opened the scoring courtesy of Woodrow's header from Dimitri Cavare.
And Woodrow was again on target to double both his tally and the visitors' advantage in the 24th minute as he rifled home from the edge of the penalty area.
Albion and Barnsley supporters joined together in a 32nd-minute applause in tribute to Baggies fan Rob Spray, who tragically lost his life in Bulgaria last week.
Grady Diangana's strike hit the side-netting in first-half injury time, although the hosts found themselves 2-0 down at the interval and looking for a route back into the encounter.
Krovinović and Conor Townsend were introduced at the break and Albion immediately applied pressure, however Woodrow almost added a third when his 54th-minute header looped off the top of the crossbar, Alex Mowatt sending the rebound narrowly wide.
Hal Robson-Kanu, who scored the weekend's winner at the Riverside, was sent on in the 67th minute and the home side instantly reduced the arrears as Pereira's corner was headed into his own net at the near post by Diaby.
Charlie Austin and Robson-Kanu both fired off target in a matter of minutes as the Baggies pressed for an equaliser.
And it duly came nine minutes from time, Pereira heading home Townsend's delightful left-wing cross, securing a share of the spoils in the first league meeting between the two sides since 2010.
Albion: Johnstone, Furlong, Ajayi, Bartley, Ferguson (Townsend 46), Sawyers, Livermore (c), Edwards (Krovinović 46), Pereira, Diangana (Robson-Kanu 67), Austin.
Subs: Bond, Hegazi, O'Shea, Brunt.