Middlesbrough missed the opportunity to close the gap on Championship leaders Coventry City after being held to a goalless draw by relegation-threatened Oxford United.
Despite the gulf between the sides in the table, it was Oxford who came closest to breaking the deadlock in the first half.
Stanley Mills struck the crossbar with a powerful long-range effort after a surging run, while Myles Peart-Harris saw a close-range attempt rebound off the post in stoppage time.
Boro, managed by Kim Hellberg, struggled to find rhythm before the break.
Jamie Cumming dealt comfortably with efforts from David Strelec and Matt Targett in a subdued opening period.
The hosts improved markedly after the interval and dominated possession, carving out a series of chances.
Hayden Hackney, Tommy Conway and Morgan Whittaker all went close, but were thwarted by a combination of profligacy and inspired goalkeeping from Cumming.
Cumming produced a superb point-blank save to deny Conway for a second time, while Oxford defender Christ Makossonarrowly avoided turning the ball into his own net with a misjudged header that drifted past the post.
Callum Brittain was also denied late on as Oxford bodies flew in to block.
The result leaves Middlesbrough three points adrift of Coventry, though they retain a six-point cushion over third-placed Millwall.
Oxford, meanwhile, edge five points from safety, taking encouragement from a disciplined and determined display on the road.
Middlesbrough boss Kim Hellberg told BBC Radio Tees:
"We knew that was going to be the game. If we score early, it could open up a little bit. We didn't, they had some chances in the first half, they could have scored.
"We had some chances through the game, especially in the second half.
"At the end it's 0-0, there's no goal, you have to take the point and move on.
"This is the part when you play against these teams when they defend with their heart all the time.
"We should have scored, that's how it is, but we didn't. It's one point to add to the tally and we keep moving on."
Oxford United boss Matt Bloomfield told BBC Radio Oxford:
"I thought we were better today than at Coventry. It's similar, but different. I thought we were excellent first half, had the two best chances of the half.
"I'll be honest with you, at Coventry I was grateful for the point. Today, I was a bit disappointed that we haven't got ourselves ahead [by] one, maybe even two, in the game.
"I think Middlesbrough are as good as it gets in the league. They are brilliant, the way they move the ball, some of the players they have got are fantastic. They are going to have spells of chances and we had to maybe ride our luck at times.
"I'm actually thinking that was a different performance to Coventry because we imposed ourselves on the game today, especially in the first half.
"That's two good performances in a row and two good performances where we can go after more."
