Emmanuel Latte Lath bagged his first goal in a Boro shirt - but Michael Carrick's side were denied at West Brom.
Ten-man Boro were left counting the cost of the goals conceded after going down 4-2 at the Hawthorns.
Possession
41%Shots
14Shots On Target
5Corners
2Fouls
82
0
Cards
1
1
It was an entertaining opening. Boro had some defending to do - Dael Fry, Darragh Lenihan, and Tommy Smith all made some early blocks – but Carrick’s men also looked a threat.
Sammy Silvera had a couple of early crosses intercepted, and Riley McGree almost capitalised on a misunderstanding at the back for West Brom.
Hayden Hackney and Silvera had a couple of shots blocked before the home side took the lead midway through the first half.
Cedric Kipre was the man who profited from a long throw that was headed down, he controlled the ball well and delivered a strike which left Seny Dieng with no chance.
The second goal came just six minutes later when John Swift was able to run unchallenged before drilling the ball past Dieng to double the advantage.
Boro were back in it less than 60 seconds later. Silvera provided the cross and Latte Lath headed the ball home.
And the lively Latte Lath almost had Boro back on terms before the break when he worked himself an opening, but couldn’t quite keep his shot down.
Boro ended the half with more good pressure, but the whistle came before the visitors could equalise the home side’s flattering advantage.
The second half got off to the worst possible start as Boro handed West Brom a third goal of the afternoon. A back-pass went straight to the feet of Brandon Thomas- Asante, who was able to round the keeper to make it 3-1 and leave Boro with a mountain to climb.
Once again, Boro almost reduced the arrears within seconds and it was Lukas Engel who was denied by the feet of Alex Palmer in the Baggies goal.
And the situation worsened for Boro when Tommy Smith, back in the side in place of the injured Rav van den Berg, was shown a second yellow card, leaving the visitors down to 10 men for the final 40 minutes.
On the hour mark, Carrick re-shuffled his pack with Paddy McNair and Isaiah Jones being introduced to proceedings.
Jones immediately warmed the hands of Palmer after cutting in from the right and he later hit the inside of the upright with a curling shot which had beaten the Baggies keeper.
Marcus Forss and Matt Crooks were also brought off the bench and the Finnish international sent a shot into the side-netting.
With six minutes remaining, Boro were handed a real opportunity, though, when referee Jeremy Smith awarded a penalty for handball and Forss stepped up to score.
Any hopes of a comeback were extinguished when Jeremy Sarmiento added a fourth in the 90th minute.
West Brom: Palmer, Ajayi, Kipré, Pieters, Furlong, Molumby, Yokuslu (Mowatt 65'), Phillips (Townsend 64'), Wallace (Sarmiento 69'), Swift (Chalobah 81'), Thomas-Asante (Maja 65')
Subs: Townsend, Bartley, Maja, Chalobah, Sarmiento, Mowatt, Fellows, Griffiths, Ingram
Middlesbrough: Dieng, Smith, Fry, Lenihan, Engel, Howson, Hackney, Silvera (Forss 72'), Rogers (McNair 59'), McGree (Jones 59'), Latte Lath (Crooks 72')
Subs: Barlaser, Jones, Gilbert, McNair, Coburn, Forss, Glover, Crooks, Jones