Match ends, Leeds United 4, Middlesbrough 0.
Middlesbrough boss Jonathan Woodgate said it is "blatant" that his injury-hit team need more players after they fell to a 4-0 defeat at table-topping Leeds.
Former Boro man Patrick Bamford headed the hosts into an early lead after goalkeeper Aynsley Pears had kept out his initial attempt.
Mateusz Klich's deflected shot left Pears with no chance as Marcelo Bielsa's men doubled their lead just before the break.
Helder Costa lashed home from the edge of the area and Klich curled in a superb effort as Leeds cruised to a fifth successive win to move a point above West Brom, who visit Preston on Monday.
"It's painful but let's not get away from it, they are a really top team. They are the best we've played in this league," former Whites defender Woodgate told BBC Tees.
"Without a shadow of a doubt we need more players in January. The chairman knows that we need more players.
"It is blatant for all to see that we need reinforcements."
Boro captain George Friend and goalkeeper Darren Randolph are both sidelined, while Woodgate said he had to play Paddy McNair in defence rather than his favoured position in midfield as he is playing with an injury and striker Britt Assombalonga was forced off with an ankle knock.
The Teessiders, who have now won just one of their past 12 games, gave debuts to Tyrone O'Neill and Ben Liddle off the bench but had no answer to the hosts throughout and could have lost by more had Leeds been more ruthless.
"Anything you get from coming to Elland Road is a bonus. We need to beat the teams around us," Woodgate, who is in his first season in management added.
"It's my job to pick them up and one thing I can take from the game is that they never gave up, they never chucked the towel in. That's a positive for me."
The only downside for Leeds was Kalvin Phillips' fifth booking of the season which means the midfielder will be suspended for next week's derby against Huddersfield Town.
Boro remain one point above the relegation zone and host Charlton next Saturday.
Leeds head coach Marcelo Bielsa:
"It is important [to be top now] but there is a long way forward.
"Of course, we have to give some value to the current position because in a league like this, the future is built match by match.
"But the most important is the regularity in every match to make a difference. You have to analyse how you win every match."
- 23PhillipsBooked at 24minsSubstituted forBerardiat 83'minutes
- 17Hélder CostaSubstituted forAlioskiat 76'minutes
- 9BamfordBooked at 22minsSubstituted forNketiahat 79'minutes
- 17McNairBooked at 27mins
- 4AyalaBooked at 65mins
- 16HowsonBooked at 75mins
- 26WingSubstituted forLiddleat 70'minutes
- 11FletcherSubstituted forWalkerat 90'minutes
- 9AssombalongaSubstituted forO'Neillat 77'minutes
- Keith Stroud
- Shots on Target
Second Half ends, Leeds United 4, Middlesbrough 0.
Substitution, Middlesbrough. Stephen Walker replaces Ashley Fletcher.
Ben White (Leeds United) wins a free kick in the attacking half.
Foul by Marcus Tavernier (Middlesbrough).
Attempt missed. George Saville (Middlesbrough) left footed shot from the right side of the box is too high.
Attempt blocked. George Saville (Middlesbrough) right footed shot from the centre of the box is blocked. Assisted by Patrick McNair with a cross.
Foul by Ben White (Leeds United).
Marcus Tavernier (Middlesbrough) wins a free kick on the right wing.
Substitution, Leeds United. Gaetano Berardi replaces Kalvin Phillips.
Attempt missed. Ezgjan Alioski (Leeds United) left footed shot from outside the box misses to the right. Assisted by Kalvin Phillips with a cross following a corner.
Corner, Leeds United. Conceded by Aynsley Pears.
Attempt saved. Kalvin Phillips (Leeds United) right footed shot from outside the box is saved in the top right corner.
Jack Harrison (Leeds United) wins a free kick in the attacking half.
Foul by Marcus Tavernier (Middlesbrough).
Substitution, Leeds United. Eddie Nketiah replaces Patrick Bamford.
Liam Cooper (Leeds United) wins a free kick in the defensive half.
Foul by Ashley Fletcher (Middlesbrough).
Ben White (Leeds United) wins a free kick in the defensive half.
Foul by Tyrone O'Neill (Middlesbrough).