Leeds returned to the top of the Sky Bet Championship after a 2-0 victory over QPR at Elland Road.
In what has been a recurring theme for Marcelo Bielsa's side this season, they struggled to truly kill off their opponents despite bossing large periods.
They have still scored just seven goals in seven games and their failure to seal convincing victories, especially at home, will be a concern.
Leeds were dealt a blow before kick-off with the news that top scorer Eddie Nketiah would miss the game after sustaining an injury in training.
Nevertheless, Leeds started brightly and had a golden early chance to open the scoring.
Luke Ayling's precise centre picked out Mateusz Klich but despite being unmarked, the midfielder volleyed over.
The home side were piling on the pressure and Rangers had debutant Lee Wallace to thank for a goal-saving tackle to keep out misfiring striker Patrick Bamford.
Bamford, who has now failed to score in his last 10 outings, had rounded Kelly and looked destined to tap into an empty net but Wallace's sliding tackle ensured it stayed out.
Leeds finally made their dominance pay after 39 minutes when Harrison cut in from the left and pulled the ball back to Roberts, who coolly slotted home his first goal of the season.
Rangers were slowly working their way into the contest and just before the hour they registered a first shot on target but Manning's effort was comfortably dealt with by Kiko Casilla.
At the other end, Roberts wasted a great chance to double his tally when he crashed a shot over the crossbar after being picked out by Kalvin Phillips.
The hosts thought they had gone 2-0 up shortly afterwards when Bamford nodded home from Roberts' centre but the flag was immediately raised for offside.
The failure to find a second goal raised the tension inside Elland Road and Rangers missed a glorious chance to capitalise and restore parity.
Substitute Todd Kane whipped in a cross that picked out Jordan Hugill but he planted a header wide.
That proved to be costly as Leeds finally got some breathing space with a second goal from Harrison.
He played a one-two before bending an effort around Kelly and into the net to seal a well-earned victory.