( CNN ) -- Rory McIlroy battled back from a poor start to claim his second straight major title in the fading gloom of Valhalla Sunday with a one-shot victory over Phil Mickelson in the PGA Championship . In near pitch darkness , the 25-year old from Northern Ireland parred the final hole for a three-under 68 to finish on 16-under 268 and deny American veteran Mickelson his sixth major title at 44 years of age . McIlroy was winning the Wanamaker Trophy for the second time and his fourth major , consolidating his status as world number one . The overnight leader trailed Rickie Fowler by three shots as he turned for his back nine but rekindled his hopes with a stunning eagle on the par-five 10th to go 14-under . But up ahead , Fowler was joined on 15-under by playing partner Mickelson and Sweden 's Henrik Stenson , who was also making a tremendous last round charge . McIlroy , bidding for his third straight victory after his British Open and WGC-Bridgestone titles , refused to be daunted and a birdie on the 13th saw him draw level . First Stenson , then Fowler and Mickelson dropped shots to go back to 14-under and when McIlroy birdied the 17th he led by two playing the last . With the light fading fast , Fowler and Mickelson agreed to let McIlroy and his last day partner Bernd Wiesberger of Austria to also hit their tee shots on the 18th , effectively playing it as a fourball . McIlroy nearly found the water with his drive and had to settle for his par , while Mickelson made his birdie to edge ahead of Fowler and Stenson into second place . American pair Jim Furyk and Ryan Palmer finished on 12-under in joint fifth . McIlroy thanked Mickelson and Fowler for their sportsmanship as he accepted the trophy and said there was never any doubt in his mind he would finish the job Sunday . `` I wanted to win this thing and get out of here , '' he said . His latest triumph completed a remarkable run for McIlroy , who had endured a difficult 2013 after first PGA Championship success two years ago . `` I 'd never dreamed I 'd have a summer like this , '' he admitted . Only the U.S. Masters title now eludes McIlroy to complete a full set of the majors and he will surely focus his efforts on the 2015 edition at Augusta in search of a hat-trick of successes at golf 's highest level .
Rory McIlroy wins PGA Championship at Valhalla . Second straight major for world number one . Has to withstand challenge from U.S. pair Mickelson and Fowler . Tournament finishes in gloom after rain delay .