Dan James (second left) scored his fifth goal of the season within ten minutes
Manor Solomon scored one and teed up two more as Leeds United coasted to a ninth successive home win and sent floundering Oxford United into the Championship relegation zone.
Welshman Dan James slid in the opening goal from close range after Solomon eluded three challenges before finding his fellow winger.
Defender Jayden Bogle doubled the lead after the break, combining with Brenden Aaronson, who shot into the bottom corner of the net.
And at 2-0 down, outclassed Oxford, with Craig Short in caretaker charge following Des Buckingham's departure and incoming boss Gary Rowett watching from the stands, became increasingly ragged.
Sloppy play in the middle of the park allowed Solomon to run through and tee up Aaronson to fire in the third before the outstanding Solomon got the goal his performance deserved, crashing the ball home from a tight angle after great work by Joel Piroe.
Leeds played with freedom and confidence before the interval, with a fraction under 70% possession and 12 attempts on goal.
Oxford keeper Jamie Cumming could do nothing to stop the opening goal, but was then a very busy participant in a one-sided contest.
Cumming made fine low saves from James and Joel Piroe, while Aaronson, Ao Tanaka and Joe Rothwell also went close as the home side regularly tried their luck from distance
Oxford's best chance fell to Przemyslaw Placheta before the break, but the Polish midfielder shot wastefully wide from close range and the visitors never looked like staging a comeback once Bogle made it 2-0 with just over 30 minutes to play.
Strikes by Aaronson and Solomon ensured a 4-0 success and Leeds finished with 23 attempts on goal, while the visitors only managed six - none of which were on target.
Can Rowett arrest Oxford's rotten run?
Oxford's form makes grim reading - and made miserable watching - for incoming and onlooking head coach Rowett.
Defeat against high-flying Leeds in the first of four matches over the festive period leaves them second from bottom of the Championship, having managed just one victory in 16 matches.
Former Derby County, Stoke City, Millwall and Birmingham City boss Rowett inherits a side that have now lost six of their past seven matches, and eight from 10.
The U's have only managed four league wins all season, but none away. All but two of their 18 points have come at home.
Leeds 'the best I've seen this year' - reaction
Leeds boss Daniel Farke told BBC Radio Leeds: "A perfect way to start the festive days. Obviously an important win. Impressive scoreline and impressive performance.
"I'm quite delighted with it. We could have scored a few more goals in the first half.
"But overall, the most important thing for us was to return to the dressing room with the clean sheet and three important points. It was good for the goal difference.
"All the offensive players chipped in with assists and goals, so it's good for the confidence."
Farke: Impressive scoreline, impressive performance
Oxford caretaker boss Craig Short:
"That's the best I've seen this year, by a long way. Those boys are Premier League players.
"I was disappointed with the nature of the goals but there's a massive gulf in class in this division. We've realised that recently.
"We're in a mini-league and the honeymoon period is over. I hope the new manager gives us a lift."
