Oxford United fell to a 2-1 defeat to Middlesbrough at the Riverside Stadium.
Michał Helik gave the U's the lead, but Middlesbrough hit back straight after half-time through Kelechi Iheanacho before a late Neto Borges winner broke Oxford hearts.
Gary Rowett made two changes to the side that started against Watford last time out, with Alex Matos replacing the injured Cameron Brannagan and Matt Phillips coming in for Ole Romeny following the latter's international exertions for Indonesia.
United created the first chance after just 80 seconds as a Will Vaulks long throw fell for Ciaron Brown, skipper for the day, but the ball was slightly behind him and he scuffed his shot into Mark Travers' arms.
It was a bright start for the U's, who almost scored in the fourth minute. Phillips did well to control Brown's pass and beat his man before his early cross fell for Przemysław Płacheta, whose first-time shot was well kept out by Travers.
United won their first corner in the 15th minute and from Siriki Dembélé's delivery the ball reached Phillips, but he could only prod it wide from inside the six-yard box.
The next 20 minutes United had to show their resilience to keep Boro at bay, limiting the home side to fairly harmless long-range efforts.
The game turned in the 38th minute and yet again it was a Vaulks long throw that did the damage. Nelson flicked the ball on and Middlesbrough could only half clear, with it coming to Helik on the edge of the area. His aim was unerring and the ball flew into the bottom corner to give Oxford the lead. There could be no complaints.
The home side looked to respond and three minutes later Iheanacho had a glorious chance; after evading a couple of tackles he just had Jamie Cumming to beat, his shot coming back off the bar.
The second half was just two minutes old when Boro equalised, Iheanacho getting on the end of a Samuel Iling-Junior cross to score his first goal since signing in January.
United had just made a triple change when Cumming did well to prevent Tommy Conway's header creeping in at the near post, and Brown made one of his customary do-or-die blocks moments later to prevent Boro taking the lead.
There were 10 minutes remaining when Middlesbrough took the lead through Borges, and again Iling-Junior was the creator, his cross flicked home from eight yards.
A disappointing result against a play-off chasing side, but now we need to go again as we face Sheffield United next Saturday at the Kassam.
UNITED: Cumming, Brown, Vaulks, Płacheta (Goodrham 65), Harris (Bradshaw 65), Phillips (Kioso 46), Nelson, Matos, Dembélé (Mills 65), ter Avest (Romeny 83), Helik
Unused subs: Ingram, Long, McEachran, Rodrigues
Attendance: 24,624, including 653 from Oxford
Report: Martin Brodetsky; Photography: JasonPix, Steve Edmunds
