The Bees got their noses ahead midway through the second half thanks to Frank Onyeka's shot coming off Lascelles and finding its way into the net.
Here is how VAVEL rated the Newcastle players this afternoon.
The goalkeeper and defence
Karl Darlow – 3
Karl Darlow never looked comfortable from the minute the game kicked off, highlighted by his error that gifted Toney his goal on 11 minutes.
Newcastle have lacked solidity in between the sticks all season with Martin Dubravka out.
But with him now fit, expect him to come in for the Arsenal game.
Fabian Schar – 5
Fans were desperate to see Fabian Schar return to the starting line-up, but it seems he needs an extended run in the team to get back to his best.
Like the whole backline, Schar was poor at times, but his ability to drag Newcastle forward cannot be ignored.
Jamaal Lascelles – 6
The Magpies captain gave his side the lead with a good header and did make some important challenges in the game.
He was a lot better today than previous games, but struggled to deal with Brentford's attack which ultimately led to them netting three.
Ciaran Clark – 4
The Irishman looked out of his depth today, failing to cope with Toney and Bryan Mbeumo in particular.
His performance – as well as the rest of the defence – pinpoints just how much Newcastle need defensive reinforcements in January.
Jacob Murphy – 5
Jacob Murphy did not offer a lot going forward and was targeted by Brentford throughout, shown when he left Henry unmarked at the back-post to give The Bees the lead.
Jonjo Shelvey – 7
After being hailed as an 'incredible technician' by Eddie Howe in his pre-match press conference, Jonjo Shelvey put in his best performance of the season, reminding everyone just how good he is in the process.
Shelvey comes across as a player you need to put an arm around if you are a manager, and if Howe keeps playing his cards right, the midfielder could be the man to turn The Magpies form around.
Joe Willock – 6
Joe Willock has not hit the lofty heights for Newcastle so far this season since he signed on a permanent deal in the summer, but he was much improved this afternoon.
At times, however, he was dispossessed far too easily and if it wasn’t for the offside flag being raised, he would have solely been at fault for a goal.
Matt Ritchie – 6
The Scotsman epitomised Newcastle's performance today: good going forward but poor defensively.
The strongpoint of Matt Ritchie's game this season has been his crossing, shown by his excellent assist for Lascelles' opener, but his work going back was sketchy.
Joelinton – 8
By a country mile, Joelinton's performance today was the best Toon fans have seen from him since he arrived for that big £40 million price tag.
The Brazilian was tireless with his work rate – offensively and defensively – and on another day, he would've scored more than just one goal.
Callum Wilson – 7
It was clear from kick-off that Brentford's plan was to keep Callum Wilson as quiet as possible, and they did that to an extent.
But even when Wilson is not putting the ball in the back of the net, he is constantly making himself a nuisance, using his physicality in particular to cause problems.
He worked hard today and was unlucky not to score with the two big chances he had in the game.
The standard is so high for Saint-Maximin that even when he has a good game, it sort of goes unnoticed. But today, it was impossible to understate how good he was.
Scoring the all important equaliser, the Frenchman was the catalyst to Newcastle notching three goals.
Just like Wilson, Newcastle need to keep their star man fit if they want any chance of Premier League survival.