A David Nugent penalty separated the sides at the King Power Stadium this afternoon after a surreal first half saw football take something of a supporting role with the drama of a power cut created all the murmurs in the stands.
The spotkick came when the floodlights had died but the fading daylight allowed play to continue and the lively Anthony Knockaert tumbled over Shaun Cummings as he burst into the box with a jinking run at pace.
The back-up generator kicked in and Nugent hit the bar before firing wide as a bizarre first half belonged to the hosts.
But Reading came back strong in the second half and arguably deserved a point - Kasper Schmeichel had to save an inswinging Drenthe free-kick, Pavel Pogrebnyak had a header ruled out for a tight offside decision, and Alex Pearce saw an effort cleared off the line by Ritchie De Laet, but the equaliser never came.
Yellow: Guthrie, McAnuff
The first and as it turned out quite significant cheer of the game came only five minutes in and came courtesy of a floodlight failure that plunged the players into a dusky gloom.
But in the same passage of play that saw the power to the stadium and surrounding area cut, the home side got their first glimpse of goal. Lloyd Dyer squirmed into a yard of space and managed to swivel on his right foot and arrow an effort on target with his left, but Alex McCarthy got well behind it to save comfortably.
The lively Anthony Knockaert tried his luck from distance but fired well wide from 25 yards out, while a couple of free kicks and corners were keeping Reading's attacking players interested.
A quarter of an hour in, Drenthe slid a nice pass into Pogrebnyak in space but the offside flag was raised against the Russian before he could fire a shot at Kasper Schmeichel's goal.
Midway through the half though and the Foxes took the lead. Knockaert ran at the Royals defence and bundled his way past Shaun Cummings before tumbling to ground. Referee Michael Naylor pointed straight to the spot and, still in murky light, David Nugent smashed home from the spot to make it 1-0.
As soon as the net rippled, the floodlights whirred back into action and Nigel Pearson's men were in control and the home fans reassured that the lead they had taken would not be ruined by power failure.
Saying that, the football was playing second fiddle to the power situation as the big screen continued to flash on and off, the PA system sporadically produced comical belches of volume, and the floodlights died again causing the referee to have a chat to both captains about the situation. Supporters even lit the torches on their phones to create a concert-like atmosphere at a gloomy King Power Stadium.
On the pitch, City were in the ascendancy, Nugent clipping the post with an effort from 12 yards out and then lashing just wide from a similar position. The striker then almost latched onto a Guthrie backpass, but McCarthy flung himself at the feet of the Foxes frontman to deny him a second on the half hour mark.
City were looking dangerous with every pacy break, but Reading were knocking at the door too, Blackman with a nice dinked ball into the box that Pogrebnyak didn't quite read, Drenthe with a corner that Gorkss came close to connecting with.
Danny Drinkwater forced a good low save from Alex McCarthy in one minute of added time at the end of a first half that was farcical at times.
The interval was spent in darkness by supporters and in the players' tunnel it was equally murky, but the floodlights running on a back-up generator lit up the stage for the second half and both teams reemerged for play to resume.
And Jamie Vardy scampered onto a long ball forward to nip in behind the two Royals centre-halves and toe the ball away from the clutches of an onrushing Alex McCarthy, but he couldn't angle a shot on target and instead passed it into the side netting with the goal gaping.
It was Kasper Schmeichel who was forced into evasive action moments later though as a dangerous inswinging Drenthe free kick just needed a touch but instead flew through to the City stopper who did well to push it over his crossbar on the bounce.
From the resultant corner, another Drenthe delivery picked out Pearce whose header seemed destined for the top right corner until Ritchie De Laet nodded it off his goalline.
Then, as Reading grew stronger, Drenthe was allowed to run from midfield, untackled into the box, and he arced a powerful effort towards the top left corner but just wide.
The Royals were bossing the second half, a surging run from Williams exemplifying that display as he burst past two or three men and into the box, only for his cross to be cut out for a corner. Guthrie's deep set piece found Gorkss who rose high to head inches over the bar.
Reading were playing some great stuff come the hour mark and Pogrebnyak had the ball in the back of the net, stooping low to head high past Schmeichel only for the linesman's flag to go up quite late and cut the away fans' celebrations short.
Leicester were still causing a threat on the break with their pace and Dyer ran 50 yards down the left before firing wide with 20 minutes left on the clock, then Knockaert barged his way to the byline but his cutback didn't find a blue shirt.
Knockaert forced McCarthy into a simple save at one end, then Schmeichel needed to attempts to pluck a Pogrebnyak header out of the air before flapping a Guthrie free kick away from the head of the lurking Gorkss late on.
Sharp and Le Fondre came off the bench as again Reading sought a point they deserved, but time ran out on the Royals.