Harrington, who has yet to win this year, will battle against the 2010 British Open champion and the highest ranked player this week Louis Oosthuizen of South Africa, an in-form Anthony Kim of the United States and Thongchai Jaidee of Thailand, a three-time Asian Tour Order of Merit champion at the Horizon Hills Golf and Country Club.
Juvic Pagunsan, the new Order of Merit leader, will lead the Asian charge alongside Jeev Milkha Singh of India, Lu Wei-chih of Chinese Taipei, who has won twice this year, and Siddikur of Bangladesh in the US$2 million event sanctioned by the Asian Tour and European Tour.
Harrington, a three-time Major champion, has been struggling to hit top form since winning the Iskandar Johor Open last year and he knows his ambitions of a successful title defence will be faced by a strong challenge this week.
"There are 156 guys here this week, and most - if not all - of them are very good players. So you're going to have to play very well and hole a lot of putts to win the tournament. It's very hard to predict who's going to win a golf tournament these days, because pretty much every player in the field is quite capable on their day," said Harrington.
He said he is unperturbed by the unpredictable weather. "We can't control the weather, as much as I'd like to be able to! So there's no point worrying about things that our outside of our control.
"Sometimes you get a good draw, other times you get a bad one - that's why it's called the luck of the draw! I'd be amazed if we don't have any delays this week, but as professionals we've just got to try to stay patient and deal with them as best we can," he added.
A weary Thongchai, who has yet to miss the cut on the Asian Tour this year, will be playing in his eight straight week but is upbeat of winning a third title in Malaysia if he can get his putter working.
"I'm feeling a bit tired. I haven't been home for eight weeks but I'm feeling very comfortable with my game. I struggled a bit earlier in the year but I've turned the corner in the last three months or so," said Thongchai, who turned 42 last week.
"I did a lot of changes in my putting in the last two years. I've tried using the long putter but now I'm feeling more confident of using the normal putter, which I will be using this week. I know that if I can putt well I will have a very good chance this week," added the 13-time Asian Tour winner.
Kim has enjoyed a solid Asian sojourn, finishing in tied third at the CJ Invitational presented by K.J. Choi in Korea in October and in the Singapore Open last week. He will be aiming to complete his renaissance after a slow start to the season with a win at the Iskandar Johor Open.
"It is a great opportunity to play in this tournament because I've heard a lot of great things about it. This tournament has a lot of good champions, Padraig (Harrington) is obviously one of them," said Kim, whose parents were born in Korea.
"I come here with a positive mind set of trying to get some momentum heading into next year because I haven't played well in the last year and a half. I've been playing quite well recently and I hope to continue that and enjoy more success next year," he added.
Henrik Stenson of Sweden, a six-time European Tour winner, hopes to overcome a flu and end a two-year title drought in what is his last tournament of the year.
"I'm not feeling too energetic at the moment, but hopefully I'll get better as the week goes on. I haven't seen that much of the course yet, because I only played the front nine on Monday and then the Pro-Am was cancelled after three holes," said Stenson, who won the 2009 Players Championship on the PGA Tour.
"My game's coming along, and I'm hitting the ball better all the time. I missed the cut last week (Singapore Open) but I didn't play that badly. I just didn't take my chances on the greens. Hopefully that changes this week, because it's my last event of the year so it'd be good to sign off the season with a decent performance," added the Swede.
The Horizon Hills will be played to a par-71 this week due to the wet fairways on the fourth hole, which has been changed from a par-four to a par-three.