Middlesbrough were indebted to goalkeeper Darren Randolph as Preston somehow settled for a Sky Bet Championship goalless draw at the Riverside.
Garry Monk's men entered the contest as favourites having won their previous three home games this campaign.
Yet it was the visitors who dominated as an off-colour Middlesbrough struggled for balance and fluidity.
Preston were the better side from the off, with a fine Randolph stop and the woodwork denying Tom Barkhuizen.
Hopes that regrouping at the interval would cure Middlesbrough's ills proved misguided as North End continued to control proceedings.
Yet a deserved winner was not forthcoming, with Randolph on hand to deny skipper Paul Huntington from six yards in the second period.
The game began in end-to-end fashion and, after Preston had begun impressively, Boro should have taken a sixth-minute lead.
Britt Assombalonga found space 40 yards from goal, raced forward, beat two defenders - only to overrun the ball into goalkeeper Chris Maxwell when trying to take on another despite having Fabio free to his left.
North End still had quality, though, and threatened as Barkhuizen cut back onto his right foot and curled wide from 20 yards.
Fabio was included as one of two changes to the Boro XI that lost at Nottingham Forest last week, but the side was sorely lacking stability as Preston impressed.
The visitors came agonisingly close in the 15th minute when Barkhuizen raced through - only to see Randolph deflect his effort onto the post.
For all their defensive uncertainty, Middlesbrough looked dangerous at the other end as Fabio and Lewis Baker came close.
But the hosts were offered another reminder of Preston's menace on the stroke of half-time, Huntington forcing a smart save from Randolph.
Alex Neil's side picked up where they left off after the interval, with Boro boss Monk responding by sending Patrick Bamford on.
Yet the change did not stem the tide as Daniel Johnson curled narrowly over before Sean Maguire again tested Randolph.
And the goalkeeper produced even better from the resulting corner, denying Huntington from point-blank range after Middlesbrough failed to clear.
Monk continued to try to alter proceedings from the bench, with home favourite Stewart Downing introduced midway through the second half.
That intervention at least helped Boro get a foothold, although the hosts' own attacking play was suddenly leaving much to be desired.
When an opening finally was created, it came from Downing as the veteran cut onto his left foot and forced Maxwell into action.
Spurred on by a suddenly vocal crowd, Boro pressed forward - yet they were almost undone on a counter-attack that ended with substitute Josh Harrop seeing a tame effort blocked.
Five minutes of added time raised an enthusiastic cheer, but the hosts could not bring another from their supporters as the game ended goalless.