Substitute Chris Wood struck late on to send Leeds through to the EFL Cup fourth round with a 1-0 win over Sky Bet Championship rivals Blackburn.
Wood broke the deadlock in Leeds' victory over Rovers seven days ago and he came off the bench to settle the cup clash with his sixth goal of the season.
The New Zealand international's timely strike gave United a third win in a row and ensured Blackburn failed to build on their first Championship victory of the season.
Rovers made nine changes to Leeds' seven and it showed during a first half that struggled to get going in front of a crowd of just 8,488, the lowest at Elland Road since the Johnstone's Paint Trophy clash with Darlington seven years ago.
Lewie Coyle went close for Leeds inside the opening minute with a brilliant half-volley that was well tipped over by Blackburn goalkeeper David Raya.
Rovers threatened when Liam Feeney headed Elliott Bennett's cross into the side-netting but they suffered a blow in the eighth minute when Scott Wharton hobbled off injured.
Stephen Hendrie fired just wide for the visitors amid a flat period that extended well beyond the half-hour mark.
Blackburn raised the tempo as half-time approached and they almost broke the deadlock when Jack Byrne tested Marco Silvestri with a curling effort that was heading for the top corner.
Leeds forward Kemar Roofe shot wide in the closing stages of the half and was off target again just after the restart as the hosts showed more intent.
Pablo Hernandez replaced the injured Ronaldo Vieira for United while Marvin Emnes was introduced by Blackburn in positive moves by both managers.
A good run by Hernandez got the Leeds fans on their feet before Eunan O'Kane had a shot blocked by a Rovers defender.
Emnes announced himself with a shot that was saved by the legs of Silvestri, who then got down to keep out Feeney's effort.
Hernandez twice went close for Leeds as the chances continued to come thick and fast.
It felt as if a goal was coming and it finally arrived six minutes from time through 71st-minute substitute Wood.
Hernandez's shot from the edge of the area was saved by Raya into the path of Roofe who scuffed a rebound which Wood finished from close range at the second attempt.
Blackburn pressed for an equaliser in injury time but Charlie Taylor was alert to prevent Feeney from turning the ball home as Leeds saw out the victory.