Blackpool’s 13-game unbeaten run came to an end with a Checkatrade Trophy defeat to West Brom U21s.
Trialist Steve Davies was on the scoresheet for Blackpool but the goal proved in vain, as the visitors claimed the three points thanks to goals from Finn Azaz and Alex Bradley.
Pool can have no real complaints about the result, with goalkeeper Christoffer Mafoumbi the far busier of the two keepers.
The Seasiders now have a fight on their hands to qualify from the group stage having claimed just one point from their opening two games.
Terry McPhillips named trialist Davies in attack, the club’s former striker able to feature on non-contract terms.
Elsewhere, Donervon Daniels made his first start since returning from his three-match suspension, partnering Paudie O'Connor in the centre of defence while also captaining the side.
His return was one of 10 changes in total from Saturday's 2-2 draw against Rochdale, with Ollie Turton the only survivor.
The likes of Mafoumbi, John O'Sullivan, Ryan McLaughlin and Joe Dodoo were all given a chance to stake a claim for a regular spot in the first-team.
Harry Pritchard also returned after missing the last few games through injury, while youth team skipper Will Avon was named on the bench.
West Brom U21s named Oliver Burke in their side, a player they signed from RB Leipzig for £15m last year.
The forward had an instant impact on the game as the visitors made a blistering start to proceedings.
He provided a right-wing cross which took a slight deflection to reach Finn Azaz just a few yards out and the striker made no mistake, side footing past Mafoumbi.
The Seasiders almost hit straight back, but Mark Cullen was unable to get a touch to a teasing cross from left from Ollie Turton.
Cullen went close again a couple of minutes later as he headed straight at keeper Jonathan Bond after reaching the flick on from strike partner Davies.
Pool were lucky to remain just a goal behind on 16 minutes as Burke sprung the offside trap to race through on goal only to see his shot deflect off Mafoumbi and out for a corner.
They were given another major let-off as the dangerous Jonathan Leko clipped the the top of the woodwork with a left-footed effort from the edge of the box, before Mafoumbi again denied Burke.
Blackpool’s goal continued to live a charmed life as Mafoumbi once again saved from Burke before Alex Bradley’s follow up was cleared off the live by Daniels.
The Seasiders almost made West Brom pay for their wastefulness as Michael Nottingham headed against the crossbar shortly before half time, while Burke was once again denied by Mafoumbi, this time at the near post after beating O’Connor for pace.
But Blackpool did bag an equaliser in first-half stoppage time, Davies converting from inside the six-yard box after a corner was diverted into his path by Nottingham’s flick on.
Davies almost turned provider at the start of the second half, laying the ball off to O’Sullivan whose low effort was saved by Bond.
Nottingham was once again involved aerially as he forced Bond into a smart save down to his left after getting his head onto Pritchard’s free kick.
At the other end, Mafoumbi produced a superb reaction stop - his fifth of the night - to deny goalscorer Azaz who was through on goal.
Cullen had a similar effort at the other end but he wastefully lashed wide of goal with only the keeper to beat.
Nottingham had the ball in the back of the net on 65 minutes as he climbed ahead of the keeper to head home only to see the linesman’s flag raised for offside.
With just 15 minutes remaining, West Brom retook the lead thanks to a smart finish from Bradley, who had time to take a touch before firing a low shot beyond Mafoumbi and into the bottom corner.
Pool tried to fight back for a second time, with substitute Chris Taylor going close with a rasping drive from the edge of the area before the same player saw a close-range shot saved in the final minute of stoppage time.
But the visitors held on for the win to condemn Pool to their first defeat since August.
Blackpool: Mafoumbi, McLaughlin, Daniels, O'Connor, Turton, O'Sullivan, Pritchard (Guy), Nottingham, Dodoo, Cullen (Gnanduillet), Davies (Taylor)
Subs not used: Boney, Heneghan, Avon, Feeney
West Brom U21s: Bond, Leko, Tulloch, Bradley (Morton), Howkins, Wilding, Meredith, Burke, Azaz, Healy, Harmon
Subs not used: Soule, Clayton-Phillips, Barry, Griffiths, Delaney, Ashton
Referee: Paul Marsden
Attendance: 717 (31 West Brom)