If Aston Villa do not qualify for the Champions League, the chances are Unai Emery will pinpoint this draw as the day that derailed their best-laid plans. His demeanour afterwards suggested this was a scoreline that will linger. Villa established a 2-0 buffer seconds after the restart but three goals in nine second-half minutes earned Brentford a shock lead.

Villa imploded but Ollie Watkins, who headed in the first goal of a crazy game, nodded in his second late on to prevent a stinging defeat. Make no mistake, though, this was a result that will jar. Villa could hardly give Tottenham, three points behind but with two games in hand, greater encouragement that fourth spot is still up for grabs. Villa could regret leaving their hopes of qualifying for Europe’s elite competition in the hands of the Uefa coefficient.

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For Villa, it was an any-win-will-do kind of afternoon. Until Watkins headed in off a post with half-time looming it proved a frustrating contest, with chances at a premium and a low block to navigate. They were a touch pedestrian, a little too predictable. Thomas Frank set up his side to stifle and hit Villa on the counter, with Bryan Mbeumo preferred to Ivan Toney in attack. The England striker was a substitute, not fully fit after a hip problem. “He is a beast – he can play through everything – but sometimes I need to be the sensible guy,” Frank said.

Toney, who came on with nine minutes left, was infuriated by his team’s futile attempt to preserve a precious lead and had words with his teammate Nathan Collins after the final whistle. Brentford are winless in nine league matches, their worst run since 2007, when they were relegated to League Two. While the fact they are now three games unbeaten might provide the more panicked Brentford supporters with some perspective, those numbers are unlikely to ease Toney’s emotions, even if Frank played down the incident. “I know it is two very competitive people who want to win a match,” the Brentford head coach said. “We have a very good culture. It is OK to have a little bit of friction.”

Brentford began with promise but the easy thing was to conclude the game was over when Morgan Rogers doubled Villa’s advantage 37 seconds into the second half. Emery was still en route towards taking his pew in the home dugout when Rogers, a January signing from Middlesbrough, scored his first goal for the club after twisting inside Kristoffer Ajer, giving Mark Flekken the eyes and promptly powering a shot inside the goalkeeper’s near post.

Brentford, however, did not lie down. The centre-back Mathias Jørgensen was the unlikely source of the visitors’ first goal, converting from close range in comical fashion. He swung his right foot at Mikkel Damsgaard’s cross but scored via his standing left leg, off his shin. No wonder Jørgensen, on his 100th Premier League appearance, left the scene smirking. Two minutes later Mbeumo wheeled away in celebration after volleying in an equaliser. He peeled off his marker, Pau Torres, and dispatched a cute, cushioned finish past a hapless Emiliano Martínez. Suddenly, everything was going Brentford’s way.

Then the impressive Sergio Reguilón, on loan from Tottenham, effortlessly brought Mathias Jensen’s diagonal pass under his control on the left flank and sent a perfect ball across the six-yard box for Yoane Wissa to sweep in. Villa’s defence was again conspicuous by its absence. Emery cursed, slouched in his seat but Watkins, signed from Brentford four years ago, jumped high above Flekken and Jørgensen to meet Leon Bailey’s deflected cross and ensure Villa did not depart empty-handed from a maddening, if not damaging, encounter.

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Rarely, though, has a point felt so inadequate. Another blow arrived deep in stoppage time, Douglas Luiz’s booking ruling him out of Villa’s next two league matches, against Arsenal and Bournemouth. Watkins’ verdict was damning: “It is one point but it should have been three,” he said. “These are the games we need to be winning – that’s what the top teams do. They finish it off, kill it off.

“We lacked that big-team mentality where they kill games off, which is really disappointing. Maybe we just don’t have that maturity or game intelligence yet.”