Aiden O’Brien scored twice as Millwall came from behind to book their place in the fourth round of the FA Cup after a convincing win over Barnsley at The Den.

Ben Thompson swept home either side of O’Brien’s goals and there was still time for Fred Onyedinma to curl home his first goal this term and the Lions’ fourth of the afternoon.

Ben Potts had opened the scoring for Barnsley early in the first-half, but they finished the game with ten men after Joe Williams saw red for a late tackle on Jed Wallace.

Here are five things we learned... 

The Lions are up for the cup… again

Millwall reached the quarter finals in 2016/17 before they were knocked out by Spurs and despite an early setback against Barnsley, the Lions scored three times in 14 second-half minutes to book their place in Monday’s draw. Neil Harris made six changes to the side that were defeated by Norwich City on New Year’s Day, but that didn’t show as they swept their Championship rivals aside.

Neil Harris wants West Ham in the next round

Harris said he would love a home draw in the fourth round and when asked which side he would specifically want, he wasted no time in saying West Ham.

Harris was on the scoresheet the last time the sides met in a domestic cup in August 2009, but Millwall were beaten 3-1 at Upton Park in the League Cup.

Ben Thompson gives Harris something to think about

If there was ever a performance that said to Harris ‘I want to be in your starting eleven’, it was Thompson’s display yesterday. Before his goal he was one of the Millwall’s best performers, but his second-half strike just added to his impressive afternoon.

He bossed the midfield, was positive whenever needed and put himself about with several tackles. You may have expected him to be a little nervous when the chance fell his way on 47 minutes, but he didn’t slot home like a man that has gone 21 months without a goal.

Aiden O’Brien is back on the scoresheet

It has been 18 games since the Republic of Ireland international scored the only goal of the game against Leeds in September and O’Brien has gone through some difficult spells during that period.

But showed his class with two neat finishes and an assist for Thompson’s goal against the Tykes. His first was a tidy finish from inside the box after Wallace’s low cross and with his confidence clearly high, his second was a stunning low drive into the bottom corner.

The Barnsley hoodoo is over

The Tykes arrived in South London on the back of five straight wins against Millwall, including September’s 3-1 league win at the Den.

They also defeated the Lions by the same scoreline in the 2016 League One play-off final, but from the moment Thompson slotted home on 47 minutes and then seconds later Williams saw red, it became apparent that run was going to come to an end.