Dubai - World number one Rory McIlroy has showed no signs of rust as he came out of a six-week break and raced straight to the top of the leaderboard on the opening day of the $8 million DP World Tour Championship on Thursday.
At the par-72 Earth Course of Jumeirah Golf Estates, McIlroy shot a bogey-free round of six-under par 66 to join his good friend Shane Lowry at the top.
Scotland's Richie Ramsay and Denmark's Thorbjorn Olesen were tied third one shot further behind at five-under par 67.
Defending champion and world number four Henrik Stenson opened with a four-under par 68 and was tied fifth along with Argentine Emiliano Grillo.
McIlroy, who has already secured the European Tour's Race to Dubai crown, was playing his first competitive event since the Alfred Dunhill Links Championship in the first week of October.
He was scheduled to play two Final Series events in Shanghai, but had to pull out to prepare for his ongoing legal battle against his former management company.
The 25-year-old Northern Irishman started hot with four birdies in his first five holes, before adding two more on the 15th and 16th holes.
McIlroy, who won both the tournament and the Race to Dubai in 2012 and is aiming for a repeat, said: "Probably should have been five (birdies) in the first five, to be honest. It was a great way to start.
"You never expect to start like that, but I've been hitting the ball well for the last couple of weeks that I've been practicing and it was just a matter of trying to take that good range play on to the course, and I was able to do that today."
Ireland's Lowry started birdie-birdie before cooling down a bit. But he finished with four birdies in his last six holes.
It was a good comeback for the 27-year-old Lowry, who was in contention at last week's Turkish Open before playing the last 12 holes at five-over par.
Lowry, who is ranked 52nd in the world and looking for a good finish to get inside the top-50, said: "Last Sunday was quite a difficult day for me. The last 12 holes was just kind of couldn't wait to get here to be honest. But once I got here on Monday, I was fine.
"Obviously, I put myself into contention which is a positive from last week. I'm just looking to give myself the same chance this week and maybe I won't mess it up."
Stenson, who won both the DP World Tour Championship and the Race to Dubai last year, was two-under par after six holes before making back-to-back bogeys on the seventh and eighth to fall back to even par. But he recovered well with a birdie on the ninth and was solid on the back nine.
"I'm pleased with that," said the Swede, who is currently second in the Race to Dubai.
"I thought I played quite solid and hit a lot of nice shots. I missed some good birdie chances early on and I made two bogeys in a row with possibly one or two bad decisions there which was a little frustrating, but bounced back and made some nice birdies coming home.
"I've got a nice way to play this golf course in an effective way, and I was just trying to stick to that. No point in trying to change your game plan just because the results are not coming. I was sticking to my plan and did pretty well from ninth onwards."
Leading first-round scores in the $8 million DP World Tour Championship on Thursday at the par-72 Earth Course of Jumeirah Golf Estates:
66 - Rory McIlroy (NIR), Shane Lowry (IRL)
67 - Thorbjorn Olesen (DEN), Richie Ramsay (SCO)
68 - Henrik Stenson (SWE), Emiliano Grillo (ARG)
69 - Edoardo Molinari (ITA), Danny Willett (ENG), Tommy Fleetwood (ENG), Louis Ooosthuizen (RSA), Ross Fisher (ENG)
70 - Tyrrell Hatton (ENG), Kristoffer Broberg (SWE), Jonas Blixt (SWE), Lee Westwood (ENG), George Coetzee (RSA), Joost Luiten (NED)
71 - David Howell (ENG), Hennie Otto (RSA), Richard Sterne (RSA), Robert Karlsson (SWE), Pablo Larrazabal (ESP), Marc Warren (SCO), Romain Wattel (FRA), Miguel Angel Jimenez (ESP), Victor Dubuisson (FRA), Thomas Bjorn (DEN), Justin Rose (ENG), Alexander Levy (FRA)
72 - Oliver Fisher (ENG), Darren Fichardt (RSA), Bernd Wiesberger (AUT), Branden Grace (RSA), Charl Schwartzel (RSA), Thongchai Jaidee (THA), Stephen Gallacher (SCO), Martin Kaymer (GER), Graeme McDowell (NIR), Jamie Donaldson (WAL)
73 - Michael Hoey (NIR), Wade Ormsby (AUS), Rafael Cabrera-Bello (ESP), Nicolas Colsaerts (BEL), Simon Dyson (ENG), Francesco Molinari (ITA), Fabrizio Zanotti (PAR), Andy Sullivan (ENG), Sergio Garcia (ESP)
74 - Mikko Ilonen (FIN)
75 - Matthew Baldwin (ENG), Matteo Manassero (ITA), Oliver Wilson (ENG), Ernie Els (RSA), Ian Poulter (ENG)
76 - David Lipsky (USA), Thomas Aiken (RSA), Luke Donald (ENG), Eddie Pepperell (ENG), Marcel Siem (GER)
78 - Brooks Koepka (USA)