Tony Pulis explains Britt Assombalonga substitution as Norwich, Leeds and Sheffield United pull away: Six things we learned after Brentford defeat

The hosts took an early lead when Ashley Fletcher opened the scoring with just six minutes on the clock, before a Ryan Shotton own goal and Said Benrahma finish in the space of four minutes turned the game on its head.

Pulis also had to deal with questions regarding an unpopular substitution midway through the second half - here's what we learned.

Pulis explains Assombalonga substitution

“It wasn’t a popular decision was it,” said Pulis after the game, when quizzed about the withdrawal of Britt Assombalonga in the second half.

Boro's top scorer made way for defender George Friend in the 62nd minute as Pulis looked to shut up shop and protect his side’s 1-0 lead.

It's a tactic which has worked for Pulis in the past but, against a possession-based Brentford side who like to play out from the back, the move only invited pressure.

"I didn’t think Britt looked sharp, quite at it like he has been.” explained Pulis after the game. “The Fletcher header (at 1-0) I expected Britt to move and tap in, it went past him.

“People say that substitution affected the game, if I made a mistake I made a mistake I will hold my hands up,” added the Boro boss following the full-time whistle.”

Fans back their star striker after early withdrawal

The Boro faithful didn’t hide their displeasure when Assombalonga’s number went up midway through the second half, as Friend's introduction prompted a chorus of boos.

That was nothing against the popular full-back, in fact Assombalonga wasn’t enjoying his finest afternoon, but Pulis’ decision to switch the emphasis from attack to defence didn't go down well.

Assombalonga wasn’t best pleased either, placing his hands on his hips before slowly making his way to the dugout, applauding the home crowd in the process.

The Riverside responded with the chant ‘du du du Britt Assombalonga’, which was sung again after Brentford’s took the lead.

Boro undone by possession-based Bees

It’s well documented that Pulis’ Boro don’t play the most eye-catching football, yet their ability to grind out results has kept them in the promotion mix throughout the campaign.

The visit of Brentford presented a side who are unlikely to finish in the top six this term, but have been praised for their free-flowing football in recent years.

For 45 minutes Boro countered that well, with Pulis’ side picking their moments to press the opposition high up the pitch.

Yet the Bees took control in the latter stages, with midfield instigator Romaine Sawyers dictating play in the middle of the park, while the front three of Said Benrahma, Sergi Canos and Neal Maupay took it in turns to drop deep.

Ultimately, on this occasion, it proved a winning formula for Thomas Frank's men, as they cut Boro open twice in four minutes to take the points.

READ: Middlesbrough winger Rajiv van La Parra posts cryptic message on social media after Brentford defeat

MORE: Tony Pulis reveals Middlesbrough's big problem compared to rivals Leeds and Norwich City

Patience is paying off for Ashley Fletcher

Since returning to the side against Blackburn last month, Ashley Fletcher has registered two goals and one assist, and could have had even more.

His sixth-minute opener against Brentford was a poacher's finish, as the striker capitalised on Daniel Bentley’s error, after the Bees goalkeeper parried out Mo Besic’s original shot.

Fletcher's link-up play and work rate was also impressive, and the 23-year-old is enjoying his partnership with Assombalonga, who he's started the last four games alongside up top.

“I feel like I’m thriving at the minute under the manager, especially playing with Britt,” Fletcher told BBC Tees after the game. “We’ve got a really good off-field partnership and on the field it shows.”

Set-plays remain an issue

Following the goalless draw at Wigan a week ago, Pulis said his ‘one big disappointment' was Boro's wastefulness from set-plays.

Despite the aerial threats of Daniel Ayala, Ryan Shotton and Dael Fry, the Teessider's failed to score from seven corners at the DW Stadium.

It wasn’t quite as bad against Brentford, yet Boro rarely looked like scoring from dead ball situations against the Bees.

Top three pull further away

Boro are now 12 points off second-place Leeds United with 11 games to go after another damaging weekend for their automatic promotion hopes.

The Teessiders do have a game in hand over the sides above them, yet it’s hard to see any of the top three imploding that spectacularly, let alone Boro putting a run together to catch them.

After Norwich’s 1-0 victory over Swansea on Friday night, Leeds and Sheffield United kept up the pressure with wins over Bristol City and Rotherham respectively.

Behind them, fourth-place West Brom dropped points following a 1-1 draw with Ipswich, which led to the sacking of manager Darren Moore, meaning it looks increasingly likely it will be a three-horse race for the automatic promotion spots.