Emmanuel Latte Lath came off the bench to score a late winner for Middlesbrough against Sheffield United in the Championship.
Boro defender Luke Ayling made a fine goal-line clearance to keep out Jesurun Rak-Sakyi's low effort before Blades goalkeeper Michael Cooper had to be alert to produce a double save from Riley McGree and Tommy Conway in quick succession in an even first half.
Alfie Gilchrist made a great block to stop Conway opening the scoring after the break and then had a shot well saved by Boro keeper Seny Dieng.
Latte Lath won it with his first league goal since the opening day with a fine diving header from Finn Azaz's cross.
United looked for a late leveller but George Edmundson followed the example of Ayling to clear off his line.
Chris Wilder's men became the last team in the EFL to lose their unbeaten start to the season when they were beaten 2-0 at Leeds United on Friday and have now slipped to back-to-back losses to drop three points off the top two.
Boro, who had themselves lost their previous two matches, are back up to eighth.
There had been just 17 goals in Sheffield United's first 10 league games this season, while the hosts had only scored 10 in 10 Championship matches so it seemed unlikely this encounter at the Riverside would be goal-laden.
That proved to be the case although not for a want of trying, particularly in the first 45 minutes.
Crystal Palace loanee Rak-Sakyi thought he had given the Blades the lead when his shot beat Dieng but veteran defender Ayling used his experience to get back and hack it off the line.
Middlesbrough had the better of things thereafter but a combination of good defending and wayward finishing looked like it was to cost them again until one real moment of quality won the match.
The home side moved the ball neatly with first-time passing and Azaz measured a perfect centre for on-rushing Latte Lath to head in three minutes after coming on.
Liverpool loanee Ben Doak almost added some gloss to the score in the final moments but Cooper made a strong save at his near post.
The Blades will look to end their sticky patch when they host Stoke City on Saturday, while Boro visit Norwich City on Sunday.
Middlesbrough boss Michael Carrick told BBC Radio Tees:
"I'm really pleased for the boys to get their rewards really. I thought we were fantastic for large parts.
"The start could have gone either way so I was proud of how the boys dealt with it and went on to play like they did. There were so many good things.
"I loved the defending and everyone played their part. There was a desire to keep the ball out of the goal.
"This is a big one for us but we won't get carried away."
Sheffield United boss Chris Wilder told BBC Radio Sheffield:
"I thought it was a game between two quality teams.
"We've had some great opportunities and played some decent stuff and defended where we've had to.
"We were patient and tried to find pockets to get the opportunity to punish them and they were the same. It was a bit cat and mouse.
"I think both teams will be there or thereabouts at the end of the season.
"We're a little bit off it at the moment and we need to get back on it quickly."