Boro’s pre-season came to an end with a late win over Heerenveen as Delano Burgzorg kept his cool from the spot.
There were plenty of further signs of progress from Michael Carrick’s side against the Dutch outfit, and they found the breakthrough two minutes into second half stoppage time.
A second half penalty from Emmanuel Latte Lath was saved and visiting goalkeeper Andries Noppert was in fine form to keep Boro at bay.
Noppert was finally beaten by summer arrival Burgzorg, though, as Boro were given another opportunity from the spot.
Boro started well and had some early sights of goal, with Isaiah Jones and Latte Lath both having stabbed efforts saved by Noppert in the first two minutes.
A better opening fell the way of Riley McGree, but he dragged wide after being slipped in by Finn Azaz.
Noppert saved an opportunist strike from Lukas Engel from 30 yards, with Seny Dieng keeping out a similar shot from Denzel Hall at the other end.
The closest either team came in the first half followed a superb ball from Hayden Hackney to Latte Lath, who was denied by the onrushing Noppert.
Boro had a golden opportunity to open the scoring on 54 minutes when Jones was tripped in the box by Noppert, but the Heerenveen goalkeeper dived low to his right to keep out Latte Lath’s penalty.
It almost turned into a double blow for the hosts when a sweeping Heerenveen move led to a strike by Ilias Sebaoui which Dieng brilliantly tipped wide.
A breakthrough continued to elude both teams, with Rav van den Berg snuffing out a dangerous attack at one end before Azaz saw a free-kick pushed wide at the other.
Aidan Morris and Delano Burgzorg both made their first appearances in Boro shirts at the Riverside, and the latter could have marked the occasion in style with eight minutes left. He beat his defender inside and out before firing a low effort which Noppert parried.
Noppert was finally beaten on 90 minutes as Morris let fly with a 25 yard strike which arrowed towards the top corner, but frustratingly crashed against the crossbar as Boro looked set to end pre-season with consecutive goalless draws.
That narrative changed deep into stoppage time, though, when Jones was fouled in the box and Burgzorg slotted home from the spot.
We kick-off our Sky Bet Championship campaign at home to Swansea City next Saturday (12.30pm kick-off).
Boro: Dieng, van den Berg (Lenihan 86), Clarke, Hackney (Barlaser 77), McGree (Burgzorg 73), Latte Lath (Coburn 77), Jones, Ayling, Howson (c) (Morris 30), Azaz, Engel (McCormick 82).
Subs: Glover, Brynn, Gilbert, Dijksteel, Finch.
Heerenveen: Noppert, Hall, Kersten, Bochniewicz, Brouwers (c), Kohlert, Smans, Sebaoui, Nicolaescu, van Ee, Al Saed.
Subs: Bekkema, Conde, Karlsbakk, van der Hart, Olsson, Mulder, Rallis, Braude.
