Boro’s U18s produced a four goal display to see off Millwall and reach the fourth round of the FA Youth Cup at a drenched Heritage Park.

The Bishop Auckland ground had seen a battering of heavy rain throughout the day, and it was credit to ground staff and officials that the game was able to go ahead as planned.

The usually pristine pitch, though, was bearing the toll of the wet weather, and the ball seemed to stick or slide over the surface as it pleased.

The soggy conditions offered the game’s opening opportunity to visitors Millwall, as Tyrese Briscoe slipped away from Boro’s Andrew Nelson before stinging the palms of Max Metcalfe.

At the other end, Calum Kavanagh was the first to test the away keeper Jordan Gillmore having chopped away from his marker, then strike partner Josh Coburn headed just over from the resulting corner.

It wasn’t long before those two combined again, with greater reward. Tall forward Coburn was afforded too much space when turning away in midfield, and after a jinking run, he fed midfielder Jack Stott in a dangerous area. Stott’s cross-shot found Kavanagh with the goal at his mercy, and the Republic of Ireland youth international made no mistake from close range.

Millwall remained a threat, and a slick passing move that belied the tricky pitch allowed Olly Bate a shot off which was well saved by Metcalfe.

But Boro proved the more ruthless in front of goal, and soon after Kavanagh doubled his and the home side’s tally - heading home from a corner flicked on by Coburn.

The Lions then squandered another opportunity to reduce the arrears when Nana Boateng went to ground and - after a long pause - the referee pointed to the spot. Boro were let off, though, as Bate blazed his effort wide before looking ruefully at the turf.

Coburn and Kavanagh continued to have joy for Mark Tinkler’s side, and each went close to increasing the lead as the half wore on with snapshots into the side netting and narrowly wide.

But it was winger Pharrell Willis who would do so before the break, an awkward bounce and subsequent mix-up in the Lions backline offering him chance to turn into an unguarded net.

There was to be one more chance of an end-to-end first 45, as Boro defender Frankie Whelan became the latest to fall foul of the conditions with a stray touch, but Metcalfe made amends with a super save to deny Tom Leahy, then Abdul Adbulmalik skewed the rebound wide.

Into the second half, and the visitors were determined to make a game of it. They went close again as Alfie Allen lifted the ball into Abdulmalik, who lofted his header over the top.

Boro would soon go close with a headed effort of our own, Kavanagh nodding wide unmarked from another threatening-looking corner.

It was to be four, though, when Stott pounced to win possession on the right flank and squared for Coburn to swivel and finish beyond Gillmore.

Millwall’s Henry Hearn, moments after coming on as a substitute, forced Metcalfe into action again with an acrobatic effort, and the Boro keeper made another fine save when, following a slip from the otherwise excellent Alfie Doherty in midfield, Abdulmalik sprinted clear.

Kavanagh was then denied his hat-trick as his vicious strike from distance was beaten away by Gillmore.

And his replacement Joe Ridley could have added a fifth for Boro after good work from Coburn to provide a low cross, but the substitute’s scuffed effort rolled wide.

The Lions were presented with another opportunity to get on the scoresheet when Boateng was scythed down just inside the box. But again the chance for any form of consolation went begging as the spot-kick winner stepped up and drilled wide.