Middlesbrough went four points clear at the top of the Sky Bet Championship with a record-breaking win at home to promotion rivals Derby.
Goals from Albert Adomah and George Friend in the last 10 minutes of an entertaining game secured a crucial victory for Aitor Karanka's in-form side, who are now unbeaten in eight matches.
Boro have also kept nine consecutive clean sheets and eight at home, with goalkeeper Dimi Konstantopoulos breaking a 30-year club record.
It was a lively start to the game and Boro pressed first in the eighth minute. Emilio Nsue found space on the right to cross for Cristhian Stuani, but the Uruguayan headed over and Stewart Downing hit a speculative cross-shot high over the bar two minutes later.
The home side had a glorious chance to take the lead in the 16th minute, when Downing found Friend on the edge of the box and he played in Kike, but the Spaniard's tame shot was parried away by Lee Grant.
Boro forged another chance in the 21st minute after some good build-up work found Adomah on the left wing, but Nsue headed wide his cross at the far post.
Derby created their first chance in the 29th minute, when Richard Keogh burst forward down the right and crossed low into the box, but Chris Martin headed wide.
A minute later they went close again, with Johnny Russell breaking into the box and hitting a low shot which Konstantopoulos saved with his legs.
Adomah was next to miss the target for Boro, in the 36th minute, when he robbed Keogh before racing clear, but his drilled shot was well wide.
Boro were enjoying an extended spell of pressure and Grant did well to tip Friend's powerful shot over the bar after good work by Kike.
Derby started to pressure the hosts as half-time approached and Boro managed to scramble clear just as Russell was about to shoot.
Boro started the second half in the same fashion and continued their search for an opener.
After winning a free-kick 30 yards out, Grant Leadbitter's effort was deflected wide and, moments later, Adomah tried an ambitious scissor kick, which was well over.
Boro threatened again in the 67th minute, when Derby failed to clear a corner and the ball fell to Adam Clayton on the edge of the box, but Keogh did well to block the midfielder's shot.
Downing went close to finding the elusive first goal in the 75th minute, when his curling effort flew just wide of Grant's right-hand post after good work by substitute David Nugent.
The goal finally arrived eight minutes from time after some neat build-up work between Leadbitter and Downing, with the former threading a great ball in behind the back line for Adomah to coolly chip Grant.
The second soon followed, when a deflected shot found Nugent and he squared for unmarked Friend to tap in from close range.
Middlesbrough boss Aitor Karanka:
"It was an amazing game, it's important for us to win. We're the best team now because we're top, but it doesn't mean anything in January with another 22 games to go."
"Middlesbrough played very well with good intensity but we weren't at that level for the start, only in spells. We edged it on chances in the first half but with 20 minutes to go I made, you could argue, a quite bold change with an attempt to create a good chance and it didn't work."