FORMER Boro boy Chris Brunt returned to haunt his old club with a deadly first-half double which set five-star Albion on their way to a comfortable victory at promotion-rivals Middlesbrough.
Like waiting for a bus, after 56 years without a win on Boro soil, two have suddenly come along in quick succession as the table-topping Baggies followed up last season's 1-0 victory with another three points at the Riverside Stadium.
Brunt opened the scoring with a deflected free-kick in the 18th minute and then took his tally for the campaign to three in the 31st minute with a goal-of-the-season contender.
Youssouf Mulumbu added a third and effectively put the game beyond the Teessiders' reach three minutes before the break when he headed home his second goal this term to help extend Albion's unbeaten run to ten games in all competitions.
It was the third game in a row the Baggies had chalked up three goals - but they did not stop there as Roman Bednar notched a fourth in the 81st minute.
And Jerome Thomas crowned a man-of-the-match display with his first goal for the club, making it five two minutes from time.
It was the archetypal all-round team performance in which every Baggies player rose to the occasion.
Luke Moore returned from injury to partner Bednar in attack.
Robert Koren made way while Thomas was recalled to the starting XI in place of the injured Marek Cech (ankle).
Albion made a shaky start and the first effort of the game came from Rhys Williams, who fired over the top from 25 yards.
Gianni Zuiverloon then made a crucial interception to prevent Marvin Emnes having a free sight of goal from Jeremie Aliadiere's pull-back from the right-hand byline.
But the visitors eventually got a foothold in the game and Joe Mattock picked out Bednar on the edge of the box with a long diagonal free-kick in the 12th minute.
The Czech striker laid the ball off for Brunt who saw a tame effort blocked by Boro new boy Sean St Ledger before Jonathan Grounds stopped his follow-up strike.
Albion were now on top and, three minutes later, Tony McMahon headed Graham Dorrans' free-kick inches over his own bar, with Danny Coyne beaten.
Williams then scythed down the tricky Thomas 20 yards out - which led to Albion snatching an 18th-minute lead.
Brunt smashed the resulting free-kick into the Boro wall and the ball deflected off Julio Arca before flying past the stranded Coyne.
Albion took control and Thomas turned McMahon inside out in the 28th minute before firing the ball into the six-yard box where St Ledger's last-ditch lunge prevented Bednar getting a touch.
The Baggies doubled their lead on 31.
Dorrans chased down Carson's long punt to put Coyne under pressure and the Wales international rushed his kick as he came flying out of his box.
The ball flew straight to Brunt on the edge of the centre circle who, without hesitation, found the back of the empty net with an exquisite first-time finish.
Southgate made a change a minute later as Aliadiere made way for new loan signing Caleb Folan.
Adam Johnson swung in a dangerous cross from the left in the 37th minute and Folan dummied to allow the ball through to Emnes, whose 12-yard shot was deflected wide off Mattock.
From the resulting Johnson corner, David Wheater stole in but headed wide of the left-hand post from ten yards.
But Boro's brief spell of pressure was well and truly nipped in the bud on 42 when more fantasy football propelled Albion into an incredible 3-0 lead.
Mulumbu wrapped up a move he started when he sent a superb ten-yard header looping into the top right-hand corner of the net from Dorrans' left-wing cross.
The Baggies started the second half strongly and, in the 51st minute, Thomas worked the ball to Mulumbu who fired just wide of the left-hand post from 20 yards.
Shelton Martis gave away a free-kick on the edge of the area in the 53rd minute and Mark Yeates curled an effort just wide of the right-hand post and into the side-netting.
Three minutes later, Yeates was in the action again when he ran in on Emnes' left-wing centre and flashed a header wide of the right-hand upright.
But Albion were soon back on the attack and Brunt's eyes lit up on the hour mark when Coyne's punch from Dorrans' corner fell to him 15 yards out for a hat-trick chance.
However, the awkward bounce made it difficult for him to keep his volley down and he fired over the bar.
Southgate's men came close to giving themselves a lifeline in the 64th minute but Carson stayed alert to clutch St Ledger's close-range header from Johnson's free-kick.
Seconds later, Robert Koren came on for Moore.
Boro made their final change in the 67th minute, with Leroy Lita replacing Emnes.
Brunt was presented with a better opportunity to complete his treble in the 73rd minute when Thomas' cross fell nicely for him - but he sliced his volley wide from 15 yards.
A minute later, Leon Barnett came on at right-back, replacing the injured Mattock, with Zuiverloon switching to left-back.
Thomas was unfortunate not to register in the 78th minute when his goalbound shot was blocked by team-mate Mulumbu. Zuiverloon then curled the rebound high and wide.
But just three minutes later, Bednar pounced on a weak headed clearance by Jonathan Grounds to rifle a shot into the bottom right-hand corner of the net from 18 yards.
Di Matteo's men also remained alert at the opposite end, with Carson twice doing well to save from Yeates and Lita in the closing stages.
And there was still time for Albion to add a fifth.
A swift break saw Koren pick out the marauding Thomas who turned McMahon inside out before firing home under Coyne.
The 1,153 Albion fans who had made the long trip to Teesside made themselves heard all afternoon and celebrated with the team at the final whistle.
BORO (4-4-2): Coyne; McMahon, Wheater, St Ledger, Grounds; A Johnson, Williams, Arca (Digard 57), Yeates; Aliadiere (Folan 32), Emnes (Lita 67). Subs not used: Jones (gk), Hoyte, Hines, Bennett.
ALBION (4-4-2): Carson; Zuiverloon, Martis, Olsson, Mattock (Barnett 74); Brunt (Wood 82), Mulumbu, Dorrans, Thomas; Moore (Koren 64), Bednar. Subs not used: Kiely (gk), Teixeira, Cox, Reid.
GOALS: ALBION - Brunt (18, 31), Mulumbu (42), Bednar (81), Thomas (88).
BOOKINGS: BORO - Williams (foul 17), Arca (persistent fouling 30). ALBION - Thomas (simulation 29), Olsson (dissent 53), Mattock (dissent 63), Dorrans (foul 67), Martis (foul 86).
REFEREE: T Kettle (Berkshire).
ATTENDANCE: 22,725 (Albion fans 1,153).
ALBION STARMAN: Jerome Thomas.