Michael Carrick's side were handed another painful reminder at Deepdale as substitute Emil Riis capitalised on a calamitous mistake at the back for Middlesbrough.

Defensive pairing, Rav Van den Berg and Dael Fry, were left staring despairingly at the Lancashire turf when they applauded a sold-out away following after a solid display turned into disaster 12 minutes from time.

For all of Boro's pressure in the early first-half exchanges and chances in the second, though, they were forced to rue missed opportunities.

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As a result, West Brom leapfrogged them into fifth spot, due to their superior goal difference. Carrick's side remain in the play-offs with a two-point cushion over nearest challengers Blackburn Rovers - who lost away at Bristol City.

It was a strong start from Middlesbrough with Delano Burgzorg and Ben Doak looking a threat on both wings. The Dutchman forced a smart save from Freddie Woodman after finding space in behind - while the talented Liverpool loanee was a constant threat down the right with dangerous deliveries left begging.

Injury to Emmanuel Latte Lath, on what could be his final outing, amid interest from MLS franchise Atlanta United, saw the departure of a focal point as Marcus Forss replaced him but he, ultimately, struggled to lead the line in the first half, before improving in the second.

Midway through the first half, Paul Heckingbottom's opponents were in the ascendancy - with the Boro midfield struggling to deal with the relentless pressure. Iceland striker Stefan Thordarson had acres of space down the left, he was invited to cut inside and duly delivered firing into the bottom right corner.

Burgzorg sent the sold-out away end into raptures after combining with Doak. The Scot slid the Dutchman in, he sat down a sliding Preston defender and slotted through the legs of Woodman.

Woodman had the post to thank after failing to get a strong hand to Doak's effort. The pacy winger burst forward, cutting inside on to his right, but the English shot-stopper pushed wide with the help of the post.

Moments later, Forss improvised to steer a right-footed effort on target, but Woodman was equal to the danger.

It looked like Boro were beginning to turn the screw and seemed the more likely to go in front for the first time. However, Heckingbottom made four substitutions, including the introduction of Riis, which promptly turned the encounter back in their favour.

Important defensive contributions from Van den Berg and Fry would, surely, be enough of a warning sign - but Boro failed to heed the danger. The substitute made an immediate impact as he arrowed an effort right into the bottom corner after Boro failed to avert the pressure.

The Lillywhites bypassed an underwhelming press from the visitors, and soon quickly turned defence into attack. Riis saw his initial effort saved well from Glover, but poor defending allowed Preston to snatch possession back in the Boro box, before the lead was restored.

After the high of the midweek win in their play-off-chasing showdown, Boro were brought back down the reality in a performance that will undoubtedly cause the Riverside boss one or two sleepless nights.