One flash of class late in a turgid affair at Silver Royd saw Scarborough clinch all four league points and move from sixth to fourth place in Yorkshire One.
A thoroughly undisciplined Middlesbrough side had four men sin-binned and only had themselves to blame for their eighth consecutive defeat on the road.
Scarborough started the game without first choice tight-head Paul Taylor, who was nursing a hamstring injury, full-back Corey Dennis with the same ailment and influential wing Harry Domett with a finger injury.
Playing with the wind in the first half the Seasiders made the perfect start when Middlesbrough infringed just inside their own half and full-back Tom Harrison kicked the long distance penalty for 3-0 in the fifth minute.
The Teesiders had the upper hand in the opening exchanges and Scarborough struggled at the set-scrums where visiting prop Isa Warsama took control.
To balance the visitors’ advantage at scrum time Locks Mikey Readman and veteran Nick Ingham bossed the line-out with their young back-row teammate Hayden Ogilvie.
However the visitors were sharper at the breakdown and spent most of the opening quarter on the front foot with scrum-half Sam Gaudie having a big influence on proceedings.
And when they surged down their left flank, full-back Jack Bricham broke from a ruck to score from close range.
Fly-half Symon O’Farrell added the extras for a 7-3 Middlesbrough lead in the 21st minute.
The second quarter was largely forgettable apart from Harrison’s howitzer-like line kicking, Scarborough struggling at the breakdown and scrums but with an unorganised Middlesbrough side unable to take advantage, the game meandered to the break with the visitors holding a four point lead.
I haven’t a clue what coach Lee Douglas said to his charges but they came out after the break playing with positivity and a physical edge missing in the first 40 minutes.
The men from Acklam Park struggled in vain to get out of their own half and when they infringed, Harrison reduced the arrears to a single point at 6-7 with his penalty in the 49th minute.
Middlesbrough then totally lost their discipline under pressure and hooker Richard Horton (deliberate offside) and centre Jack McPhillips were sin-binned in the 50th and 58th minutes respectively.
Horton returned to action on the hour but his side by then were under severe pressure.
Scarborough should have pressed their numerical advantage home, but not for the first time this season chose to repeatedly take the ball into contact inside rather than release their potent back division against a depleted defensive line.
Referee Andy Hodgson then brandished his fourth yellow card to Middlesbrough number eight Phil Harland in the 72nd minute, once again reducing the Teesside contingent.
The Seasiders looked to press home their numerical advantage but continued to struggle to make it count against a determined Middlesbrough side that were more than lucky not to have conceded a penalty try on their own line, persistently pulling down mauls, driving in and skewing scrums.
To their credit the visiting seven lived on the edge making it difficult for Mr Hodgson to adequately referee the forward exchanges.
However the official was totally on the ball when he yellow carded Scarborough scrum-half Martin Robinson for some over vigorous rucking close to the Middlesbrough line in the 72nd minute
Scarborough finally got their reward for an extended period of pressure with less than five minutes of the game remaining when a slick move involving Harrison and Chadwick released centre Graeme Jeffery to loop round and score wide on the right with the most incisive Scarborough move of the game in the 76th minute.
Harrison kicked the touchline conversion with aplomb for a 13-7 lead.
All over? Not a bit of it, Scarborough butchered the Middlesbrough re-start and ended up defending on their own line in the dying seconds.
Following a series of Middlesbrough penalties, the ball was moved infield under the shadow of the Scarborough posts but Chadwick, now at full-back, halted Middlesbrough centre Connor Foley’s charge for the line with a crunching tackle and saved the day for his side.
Foley knocked on and Scarborough cleared their lines from the ensuring scrum to win a close-fought game.
Following a sterling performance at Malton last week, Scarborough’s first half performance was desperately poor.
After the break they looked a different side and were sharper all over the paddock. Pick of the forwards were Readman, Ingham, Eamon Chapman, prop Mark Hopper and back row Ogilvie.
Behind them scrum-halves Jordan Wakeham and Robinson excelled while Harrison, try-scorer Jeffrey and Chadwick came to the fore after the break.