Danny double does it!
Birmingham City 0
The midfielder delivered a dangerous inswinging free kick from the left flank on the half hour and, sailing over Adam Le Fondre's head and without anyone getting a touch, it nestled inside the right corner of Darren Randolph's goal for the lead.
Reading threatened more, with Pavel Pogrebnyak, Hal Robson-Kanu, Chris Baird and the lively Garath McCleary all going close before Guthrie made sure of the points - his 75th minute curling free kick was elegantly spun over the Birmingham wall and arced gracefully into the top left corner and beyond Randolph's flailing dive.
City had little in reply, the back four solid throughout and McCarthy only called upon to parry the occasional effort from range, and a professional performance saw Reading coast to three more points and their third consecutive win.
Subs: Doyle, Bartley, Lee, Shinnie.
Yellow: Spector, Zigic.
Reading began well. Twice incisive balls through the City back line went to waste, one as Pavel Pogrebnyak was penalised for a shove, the next when Le Fondre was flagged marginally offside. At the other end, Lingard arrowed an early volley high over Alex McCarthy's bar as each team sounded the other out.
The first real opening was a big one. Garath McCleary threaded a nice ball between defenders and into the feet of Pogrebnyak, who got it onto his left boot and struck a sweet effort at goal, only for Darren Randolph to pull off an excellent save, diving full stretch to his right.
Moments later, McCarthy had to be alert to parry a fierce Chris Burke effort, who collected the recycled ball again only to be denied by an Alex Pearce block on the second occasion.
But it was Reading who were setting the pace, Chris Gunter escaping down the right and crossing early for Randolph to palm it against Dan Burn and just over the crossbar for a corner.
And from the resultant Guthrie corner, Madejski Stadium debutant Chris Baird came a whisker away from powering a near post header home.
Midway through the half, superb work from Hal Robson-Kanu on the left flank saw him cross into the box and the ball found Pogrebnyak in the middle. The Russian was quickly crowded out and he teed up McCleary instead, who dragged a low effort harmlessly wide in the end.
An offside Pogrebnyak headed a McCleary cross goalwards but the flag meant Randolph's flying save was unnecessary - the big Russian was causing some problems for the City defence though.
And Le Fondre was found with another McCleary slide rule pass out to the right side of the box; Alfie squared it looking for Robson-Kanu and despite a mix-up between the floored Burn and a frantic Randolph, Hal couldn't scrap it over the line from close range before the Birmingham keeper gathered it.
Reading's dominance finally paid off after half an hour. Guthrie delivered a sumptuous inswinging free kick from out on the left, Le Fondre looked to glance it goalwards at the near post, but the ball sailed past everyone and beyond the rooted Randolph into the bottom right corner.
McCarthy saved well from an Adeyemi effort from distance, but the Royals went in at the break deserving of their lead and full of confidence.
The second half began much as the first had ended, with the hosts on top. But Chris Burke threatened to level when he arrowed an effort just over the bar from a cross that had reached him on the right side of the Royals' box.
The lively McCleary scuttled in from the left and let rip from 22 yards out, but his low right-footed strike fizzed just wide of the bottom left corner.
Then a half-cleared free kick fell to the feet of McCleary who smashed it first time back through a crowded box and heading for the bottom corner until Randolph somehow managed to claw it around his post.
Towering striker Nikola Zigic was introduced and he came close to making an instant impact, rising above the backpedalling Pearce to reach a cross from the left but the centre-half did enough to force the substitute to direct his header over the bar.
Burke tried his luck from 25 yards out but fired high over the bar, and with just one goal in it the visitors kept searching for a point that may still have been achievable.
But with a quarter of an hour remaining, Guthrie gave Reading a cushion with a sublime set piece. If his opener had benefited from a little fortune, his second was curled home with pinpoint accuracy. Hal Robson-Kanu won a free kick on the edge of the Birmingham box and Guthrie delicately lifted it over the City wall and arced it beautifully into the top left corner for 2-0.
McCarthy had to push a Wade Elliott 25-yard effort wide in the closing stages, but Nigel Adkins' men were comfortable and almost added a third in injury time when Stephen Kelly's pull back was hooked just over by Pograbnyak. The the three points were staying firmly in Berkshire.