The tie was delayed by 20 minutes due to Gillingham's late arrival at the stadium and manager Neil Harris later revealed the players "had to climb over barriers and help each other get over fences" as they walked the final part of their journey.

"We got to about a quarter of a mile from Chiswick Roundabout and we got stuck," said Harris, whose side sit 78 places below Brentford in the football league.

"Fortunately we had a tactics board on the bus but we couldn't move and they couldn't get a police escort to us. We got in touch with the officials and decided to walk."

He added: "We had to leave two hours early this morning because of protestors. It's been a bit of a carnage day.

"It's a memorable night because of the performance, but also because of the factors surrounding it."

Thomas Frank said his side - quarter-finalists last year after reaching the last four in 2020-21 - were in the competition to win it and he set up his team accordingly, welcoming England World Cup hopeful Toney back from suspension in a strong line-up in West London.

Brentford swiftly asserted themselves but they were unable to build on Toney's early breakthrough, which came after a long ball from goalkeeper David Raya freed Damsgaard to tee up his team-mate two days before England's World Cup squad announcement.

Saman Ghoddos hit the post with a header after Toney had another effort saved as Brentford went close to a second before the interval.

But the Bees were unable to put the game beyond Gillingham, who scored with their sole attempt as Alex MacDonald's cross found fellow substitute Mandron with 15 minutes remaining.

MacDonald held his nerve with the first sudden-death penalty following a series of well-taken spot-kicks, before Damsgaard struck the crossbar to send Gillingham's jubilant players into Thursday's fourth-round draw.

'The beauty of cup football' - Gillingham take their chance

Gillingham have struggled on their return to the fourth tier following relegation from League One last season.

Harris' side have managed two wins from 16 matches so far this term, scoring just six goals, and they slipped to 22nd following Tuesday's league fixtures.

They had just 19% possession at the Gtech Community Stadium, registering one shot compared to 16 for heavy favourites Brentford - seven of which were on target.

But they successfully prevented their top-flight opposition from putting the game out of reach to set up their shootout triumph, which sent them into the last 16 for just the second time in the club's history - and first time since 1996.

Despite fielding a strong line-up it is now one win in nine matches for Brentford, who face a trip to reigning champions Manchester City on Saturday in their final game before Premier League football pauses for the World Cup.

"First of all congratulations to Gillingham, it's well done by them," said manager Frank. "I don't think you could doubt that I wanted to win with the team I put out but Gillingham did their job very well, they took their chance and they were spotless in the penalty shoot-out."

He added: "It is very frustrating. We wanted to go far in the competition but this is cup football and why we love cup football. That's the 'beauty' of it, and I hope Gillingham enjoy it."

Toney scores in final World Cup audition

Ivan Toney has scored 56 goals in 104 games for Brentford

In his last opportunity to impress England manager Gareth Southgate before he names his final 26-man World Cup squad on Thursday, Toney was able to make the scoresheet and offered a reminder of his spot-kick prowess as he made a final bid for inclusion.

Brentford boss Frank claimed Toney had already done enough to be selected for his first World Cup after the striker scored twice in a 2-0 Premier League win over Brighton in mid-October.

But that remains an out-of-form Brentford's only win in two months - and Toney has not scored in 270 minutes of Premier League football since that double took his tally to eight goals in 10 games.

Unused by Southgate despite being called up to the England squad for the first time for September's Nations League fixtures, Toney missed another valuable chance to shine on Saturday as he sat out the draw with Nottingham Forest due to suspension.

Currently assisting the Football Association's enquiries into allegations of historic match betting, he was able to refocus on Tuesday as he seeks to achieve his "childhood dream" of representing England on football's biggest stage.

While his early contribution was not enough to see Brentford progress, he will hope he has done enough over the past months to convince Southgate.