Andy Yiadom sent Barnet into round two of the League Cup with an extra-time winner at League One Millwall

The Lions were three divisions above Barnet prior to relegation at the end of last season but were made to look ordinary by a committed, high-energy display from Allen's side.

John Akinde put the Bees ahead from the penalty spot after 11 minutes and it stayed that way until the 76th minute when Steve Morison atoned for missing a Millwall penalty by ghosting in to nod home the equaliser.

With the score tied at 1-1 after 90 minutes the game went to extra time and it was Barnet who drew first blood when Andy Yiadom side-footed home Akinde’s low cross.

And the vice-captain's effort proved decisive, firing the Bees into round two in their first year back in the competition after two years in the Conference. 

Allen made three changes from the side which were beaten at Leyton Orient on Saturday in their League Two opener, handing debuts to Michael Nelson and Tom Champion.

Luke Gambin also came into the side with Bondz N’Gala, Mauro Vilhete and Michael Gash all dropping to a six-man substitutes’ bench.

With former Lions pair Shaun Batt and Kevin Lisbie both injured, the Bees were a man light but could call upon Ben Tomlinson once more after he recovered from a throat abscess.

Former Millwall loanee Graham Stack began in goal with Gavin Hoyte, Nelson, Bira Dembele and Elliott Johnson across the back four.

Andy Yiadom, Sam Togwell, Champion and Gambin made up the midfield with captain Curtis Weston – the youngster player in FA Cup final history during his Millwall days – playing off of John Akinde as the lone striker.

Much like at Leyton Orient on Saturday it was Barnet who had the best of the first period. Unlike Saturday’s fruitless trip to Brisbane Road the Bees made their pressure tell, though.

Allen’s men first went close when the masterful Nelson – who breezed through the first 45 minutes with the air of a man who had been there, done that and very much got the t-shirt – chested down a ball forward, taking a Millwall player out of the equation with his deft touch.

The former Cambridge United man then lofted a long ball forward perfectly into the path of Akinde and the powerful forward made enough room to shoot on the edge of the penalty area before firing narrowly over the bar.

Millwall went close themselves in the eighth minute. Former Manchester United man Lee Martin floated a teasing free-kick into the penalty area for John Marquis to flick a header goalwards, only for Stack to fling himself full-length and push the effort wide.

The Lions were made to rue that close-shave just three minutes later when Akinde picked up where he left off last season; winning and converting a penalty.

Initially second favourite in a foot-race with Millwall centre-back Byron Webster, Akinde nudged the ball past the lanky defender before drawing contact inside the penalty area. Last season’s 33-goal top scorer then rolled the penalty past Lions debutant Jordan Archer with unerring nonchalance.

Chances continued to go the Bees’ way with the livewire Gambin at the centre of everything good for the visitors.

After 25 minutes the diminutive wideman wriggled between two Millwall defender and shifted the ball onto his left foot before shooting against the far post with a deflection earning the Bees a corner. Former Lion Weston then flicked a header wide from the resulting set piece.

Millwall still retained a threat on the counter attack and should have drawn level 11 minutes before the break when a rare defensive mix-up afforded Martin the space to shoot low at Stack. But the former Lions loanee spread himself brilliantly and blocked before Togwell cleared up on the line.

And just a minute before the hosts were booed off at the break, Hoyte ought to have given the home support real cause for concern by doubling Barnet’s lead.

The full-back found himself on the edge of the penalty area when he chested down, taking out two Millwall defenders in the process, before seeing his shot deflected just wide of the near post. Had the former Gillingham defender shot sooner he would, surely, have tested Archer in the hosts’ goal.

Barnet made a strong start to the second period and although Millwall momentarily threatened with a volley from a corner which was blocked, the Bees looked the more dangerous in the early minutes.

Nelson went close to extending the visitors’ advantage when he caught a volley flush from 12 yards and was only denied by a fine block from former Tottenham Hotspur keeper Archer.

With an hour on the clock Millwall were handed the chance to level with a penalty of their own, awarded after the dangerous Fred Onyedinma burst past Gambin, who was penalised for a trip.

The experienced Morison, back for a third spell at The Den, stepped up but blasted against the crossbar and the ball bounced the safety. Stack had guessed correctly.

Fresh legs were introduced in the shape of Vilhete with little over 20 minutes remaining and the Portuguese underlined his worth when he sprinted down the left before feeding Akinde. The Bees’ number nine waited too long to shoot but still drew a good stop from Archer after cutting into the penalty area.

Millwall had a golden chance of their own soon after when substitute Paris Cowan-Hall nipped down the right flank before crossing to Onyedinma at the back post. But the youngster’s connection was poor and he could only side-foot wide.

With 14 minutes remaining Neil Harris’ side finally dragged themselves level as Morison met an inviting free-kick delivery from Shaun Williams and headed deftly past Stack.

The hosts went close again soon after when Cowan-Hall was denied what would have been the winner by a fine Dembele block on the line after Lee Gregory’s header across the face of goal found him in space.

Barnet were by no means holding out for extra-time, though, and only a superb claw away from Archer prevented Hoyte curling a left-footed effort into the top corner from the right-hand side of the penalty area.

And the end-to-end nature of the contest continued right up until the 90th minute as goalscorer Morison made the most of an uncharacteristic Nelson slip, only to see his placed shot tipped wide by Stack at full-stretch.

Barnet had more than held their own in extra-time and re-took the lead after 12 minutes. Akinde once again got the better of Webster, who at 6ft 4in had some presence about him, before cutting back for Yiadom to ram home from point-blank range.

Millwall were not without their chances in the second period as Gregory and Ed Upson both squandered good opportunities by shooting straight at Stack.

Round two awaits.

Barnet: Stack; Hoyte, Nelson (N’Gala 89), Dembele, Johnson; Yiadom, Champion, Togwell, Gambin (Vilhete 69); Weston (c) (Gash 63); Akinde.

Subs: Stephens (GK), Tomlinson, Muggleton.

Millwall: Archer; Nelson, Webster, Craig (c), Ferguson; Onyedinma (Beevers 94), Williams, Upson, Martin (Cowan-Hall 66); Marquis (Gregory 66), Morison.

Subs: Forde (GK), Cummings, Powell, Philpot.

Referee: Andrew Madley.

Attendance: 4,454 (527 away supporters).