Boro’s threadbare squad was unable to turn around a first-half deficit as Plymouth Argyle bagged a first Riverside win since 2009.
Goals from Matthew Sorinola and Ryan Hardie were enough to seal the points for the visitors.
Middlesbrough: Glover, Ayling (Dijksteel 80'), van den Berg, McNair, Thomas (Engel 80'), O'Brien, Barlaser, Forss, Azaz (Latte Lath 59'), Silvera (Gilbert 80'), McGree (Greenwood 59')
Subs: Dieng, Clarke, Latte Lath, Gilbert, Dijksteel, Engel, Greenwood, McCabe, Woolston
Plymouth: Hazard, Pleguezuelo (Phillips 85'), Gibson, Galloway, Sorinola (Edwards 73'), Randell, Houghton, Miller, Whittaker (Devine 73'), Hardie (Waine 83'), Gyabi (Mumba 83')
Subs: Cooper, Mumba, Sousa, Edwards, Callum Wright, Bundu, Devine, Waine, Phillips
On a sun-kissed afternoon at the Riverside, Michael Carrick made a double change to the side that defeated league-leaders Leicester City last weekend, Marcus Forss and Luke Thomas, who was unavailable to face his parent club, replacing Matt Clarke and Lukas Engel - and with eight first-team absentees, U21 regulars Luke Woolston and Law McCabe were named on the bench.
It was a pulsating, end-to-end encounter at Home Park in the reverse fixture and it only took three minutes for the Teessiders to carve out the opening chance this time around, Luke Ayling nodding wide at the back post.
Yet, making the mammoth 750-mile-round trip to the Riverside, the visitors were the ones celebrating the game’s opening goal - Sorinola primed to convert after Tom Glover had made an initial save to keep out Darko Gyabi.
Boro responded well. Lewis O’Brien, Sammy Silvera and Riley McGree all saw shots charged down from outside the area and there continued to be space for the Teessiders to exploit when possession changed hands.
O’Brien’s surging drive forward found Forss six yards out, Conor Hazard saving well before a raising of the flag for offside.
Though Plymouth always posed a threat on the break and so it proved - Hardie doubling the advantage on the half-hour mark with Glover making a fine double save to prevent a third before the interval.
As Boro vied for a route back into the contest, Finn Azaz volleyed wide, against his former club, and Riley McGree dipped over the bar at the end of a great move.
And while Carrick’s men held the lion’s share of possession, Plymouth continued to create openings on the counter – Paddy McNair’s vital touch ensured Hardie found the side netting and Jordan Houghton drove beyond the upright.
With 30 minutes remaining, the Boro head coach looked to the bench. Emmanuel Latte Lath was introduced for his first league game of the year and the Ivorian was joined by Sam Greenwood in attack.
By this point, the away side were happy to shut up shop and camp bodies around the box, but Boro determinedly kept probing – Silvera unable to divert Barlaser’s wicked delivery on target.
Hardie might have made it three if not for Glover's instinctive reaction save and the Pilgrims' wall held firm as Greenwood struck a free-kick in stoppage time.
Possession
32%Shots
22Shots On Target
11Corners
6Fouls
101
0
Cards
1
0