With West Bromwich Albion not in action until Tuesday (AEDT), Leeds took full advantage of the chance to reach the summit with a fifth consecutive victory.
West Brom will have the chance to go back above Marcelo Bielsa's men when it travels to face Preston North End.
Josh Dasilva scored a hat-trick for Brentford as Luton endured a chastening afternoon, and Bristol City was also a big winner, thumping Huddersfield Town 5-2.
Barnsley, Blackburn Rovers, Cardiff City, Reading and Sheffield Wednesday were the other triumphant teams, with Derby County drawing against Queens Park Rangers as Birmingham City and Millwall also shared the points.
KLICH KEY IN LEEDS ROMP
Leeds, unbeaten in eight matches, continued its fine form by cruising past struggling Boro courtesy of Mateusz Klich's double.
The outcome was rarely in doubt from the moment Patrick Bamford headed in Pablo Hernandez's cross from close range in the third minute.
Klich struck in first-half stoppage-time and later added a superb clincher after Helder Costa had scored his first Championship goal for Leeds in the 67th minute.
Leeds is a point clear of West Brom and five ahead of third-placed Fulham.
BUOYANT BRENTFORD AND BRISTOL CITY
Brentford had scored five by half-time against Luton and eventually settled for seven at Griffin Park.
Former Arsenal youngster Dasilva's treble included a late penalty, while Said Benrahma also scored from the spot.
Dasilva also assisted a strike for Ollie Watkins, who created two goals himself, with Bryan Mbeumo and Mathias Jensen the other Brentford players to find the target.
Bristol City scored all five of its goals by the 49th minute as it demolished Huddersfield at Ashton Gate.
Andreas Weimann ended with a goal and an assist as Lee Johnson's men moved up to fifth in the table, with Brentford two points and two places behind.
Elsewhere, Cardiff won 1-0 at Nottingham Forest, Nathaniel Mendez-Laing's goal meaning the hosts missed a chance to go third.
BOOST FOR BARNSLEY AT THE BOTTOM
After 18 matches without a win, bottom-of-the-table Barnsley recorded a surprise 3-1 home victory over Hull City.
That moved it two points behind Stoke City, which lost 2-1 at home to Blackburn, with Wigan Athletic also in the bottom three after being stunned by Reading's George Puscas.
Joe Garner's close-range strike had Wigan on course for victory and it led with 12 minutes to go, only for Puscas to score a hat-trick in the space of five minutes as Reading won 3-1.
Eberechi Eze gave QPR a 1-1 draw at Derby, which had new player-coach Wayne Rooney watching from the dugout, while on-loan Chelsea defender Jake Clarke-Salter's late header saw Birmingham avoid defeat at home to Millwall in a match that finished with the same scoreline.
In the early game, two goals from Steven Fletcher helped Wednesday win 3-1 away to Charlton Athletic.