( CNN ) -- Rory McIlroy held his nerve to maintain the lead on day three of the PGA Championship at the Valhalla Golf Club in Kentucky and will take a slender one shot cushion into Sunday 's final round . The Northern Irishman , who is attempting to win his third straight tournament and second major of 2014 , carded a round of 67 Saturday to leave him on 13-under-par for the week . Austria 's Bernd Wiesberger is a shot back at 12-under-par followed by Rickie Fowler on 11-under . Phil Mickelson finished the day at 10-under-par alongside Jason Day while Louis Oosthuizen , Henrik Stenson , Ryan Palmer and Miko Ilonen are tied for fifth position at nine-under-par . `` I 'm really happy with how I finished again , '' McIlroy told Sky Sports upon reaching the clubhouse . `` I finished really strongly which puts me in good position for tomorrow . '' McIlroy won the British Open in July and reclaimed the world No . 1 spot last week when he picked up the WGC Bridgestone Invitational title . And his big-hitting game seemed made for the tender greens in Louisville that had been softened by early morning rain . But the day was not without its challenges and McIlroy had to dig deep to fend off the chasing field . The 25-year-old saved par on the fourth after teeing off into the hazard before carding birdies on holes five and seven . He bogeyed eight and then once again showed guile to par the ninth when he overshot the green . A birdie on ten was then followed by a bogey on 12 and another difficult par save on 13 . At this stage Day , Fowler and Palmer had clawed McIlroy back to tie for the lead at 10-under-par . But the Rory McIlroy of the last month has been nothing if not resilient . He spoke Friday about how golf has become his life since splitting from fiance Caroline Wozniacki in May . And when the pressure was on here in Kentucky , he excelled . A birdie on 15 was followed by a miraculous approach shot on 16 that dropped two feet from the hole . Three birdies from Wiesberger on the final three holes , however , brought the Austrian level atop the leaderboard . But McIlroy added one last birdie of his own on 18 to secure the overnight lead . `` I knew there were guys ahead of me making birdies and it gives me a lot of confidence knowing that if I get challenged and people put the pressure on I am able to respond like I did today , '' McIlroy said . `` If I can keep playing well and staying mentally strong , there is another major to maybe come my way . '' By comparison , Wiesberger will be aiming for his first ever major win when he heads out Sunday . The 28-year-old is ranked 70 in the world and had only ever made the cut once in five previous majors . `` I played beautifully today , I did n't miss a lot of shots , set up a few nice opportunities on the last few holes especially . I 'm very proud of myself the way I played , '' Wiesberger said in quotes carried by UK news agency , the Press Association . `` It 's a completely new situation for me , only my second cut in a major in six attempts , so I am quite a rookie in this particularly situation . I have driven it really nicely this week and if I can do it again it will settle down the nerves and I am going to have fun tomorrow . '' Elsewhere on the course , former world No . 1 Adam Scott scored a fine 66 to leave him tied at seven-under par with Lee Westwood , Hunter Mahan , Kevin Chappell and Jim Furyk . Wales ' Jamie Donaldson is a shot ahead at 8-under-par after scoring an impressive 66 alongside Graham DeLaet and Steve Stricker . At the other end of the leaderboard , Bubba Watson 's frustrating form continued as he scored a disappointing round of 73 leaving him two-over-par for the tournament .
Rory Stewart takes slim lead into final round of PGA Championship . British Open winner holds one shot advantage over Germany 's Bernd Wiesberger . Robbie Fowler , Jason Day and Phil Mickelson all in chasing pack .