AS golfers, they're at opposite ends of the spectrum, as different as chalk and chocolate. Padraig Harrington (38) is one of golf's toughest fighters, while Rory McIlroy (20) is a sublimely-gifted 'kid'.
Yet both face the same daunting mission in the coming months as prominent members of the elite group of players expected to fill the void left by Tiger Woods' absence.
By the grace of his unflinching spirit and an uncanny short game, Harrington has won three Major titles and probably has a few more up his sleeve, Tiger or no Tiger.
He certainly stepped up to the plate when knee surgery sidelined Woods for eight months in June 2008.
So it is reasonable to expect Harrington and other proven Major winners such as Phil Mickelson to deliver in Tiger's indefinite absence. After all, they've long been conditioned to handle the pressure.
Yet McIlroy will be thrust into a glaring new spotlight this season as he takes out full membership of the US PGA Tour for the first time.
To the golf enthusiast, watching McIlroy play is like seeing Lionel Messi or Wayne Rooney in full flow.
In their quest for excitement and a new icon to replace Woods, America will inevitably turn to Holywood's swashbuckling starlet.
Many of his professional peers would crumple under this challenge, but Harrington expects his young compatriot to relish it.
"You've got to remember you're looking at a guy who is No 10 in the world," says Harrington. "And with 20 years or more left in the game, it's valid to believe Rory will be World No 1.
"I believe he loves to be challenged," the Dubliner says. "At every level he's played, Rory's been the big fish, so it would be alien to him if it was any other way.
"He was the next big star in Europe last year and this season, potentially, he is going to be the next big star in the States. It has been like that all the way up the ladder. All that changes this year is the stage."
For all of McIlroy's ability, Harrington believes the youngster's greatest gift is his enthusiasm. "Rory enjoys the game so much, he plays like a kid, and I'm not referring to his age.
"It's wonderful. He always tries to rip his drive down the tightest line on every hole. There's rarely any thought of him taking out a three-wood. I'd say poor JP (Fitzgerald, McIlroy's caddie) would nearly have to break that driver to stop Rory hitting it.
"He has no fear and doesn't see the trouble. I suspect he never will, he's such a great driver of the ball. That's his asset.
"Golf is great like that," Harrington continues. "No matter how much talent a player is given, he'll always have a weakness. You'll not find a player that's been complete."
Even Tiger. Apart from his obvious weakness for buxom blondes, Woods has long grappled with an unruly driver, while Harrington became so obsessed with correcting a small glitch in his own swing last year, he completely took his eye off the ball for the first seven months of the season.
While McIlroy is a good putter, he is not a great one, which is the inevitable result of hitting so many greens, Harrington suggests.
"Miss a lot of greens and you'll be a great putter," he says. "Seve (Ballesteros) is the perfect example. You do it out of necessity. Bad putters usually are guys who hit the ball consistently well. If you hit the ball to 20 feet on every green, it doesn't matter how good a putter you are, you're going to two-putt nearly every one of them and walk off thinking you're rubbish.
"The statistic that counts most is how many times in the course of a round you are hitting your first putt from inside eight feet," Harrington adds. "You'll usually hole 80pc of those putts, sometimes more.
"Hit it to 20 feet 18 times and you'll probably shoot two-under. However, hit it inside 10 feet nine times for par and nine times for birdie, and you'll shoot five or six-under, assuming you miss two for bogey and make seven for birdie."
Harrington has a natural grá for putting, but growing up on Stackstown helped him develop a superior short game.
"Your home course determines a huge amount," he says. "It didn't matter who you were, nobody could keep the ball on the fairways in Stackstown during the summer, while you couldn't hit more than six or seven greens, they were difficult to chip on and no putt was easy.
"You couldn't hit so you had to learn to miss properly."
Yet he still has a near-mystical ability to "will the ball into the hole more than other people," Harrington admits. "There's something about me and other putters, we're absolutely desperate to get that ball in the hole, like a natural striker in soccer wants to score goals.
"I played for years hitting seven, eight or nine greens a round. A lot of players would get tired putting from four feet, six feet and eight feet, but I've always been happy to go on, hole after hole, round after round, knocking them in consistently.
"It's stressful. Look at me over a two-footer, I'll take loads of time lining them up. I can't just slap them in because I'm afraid I'm going to miss. Yet I've always been able to deal with that element of it.
"What's great about Rory is that he knows where he's weakest and he's working on it," says Harrington, undeterred by suggestions that the youngster found the daily practice drill recommended by putting guru Dr Paul Hurrion had left him feeling "a little too wooden" over the ball.
"It doesn't have to happen today," the Dubliner insists, adding: "Rory is young enough and if he sticks at it, it will happen. He has plenty of time."
Harrington is in Portugal this weekend preparing for next month's Northern Trust Open in Los Angeles.
McIlroy, meanwhile, returns to action at next week's Abu Dhabi Championship, before his first-ever title defence at the Dubai Desert Classic title in a fortnight. Then it's off to the States for another date with destiny at next month's Accenture Match Play.
Pressure? "Rory's lovin' it," says Harrington. "Maybe he should be sponsored by McDonald's. Come to think of it, I'm lovin' it too!"
HARRINGTON'S RUN-up to RYDER CUP
February -- 4-7: Northern Trust Open, Riviera CC, (Purse $6.4m). 11-14: AT&T Pebble Beach National Pro-Am ($6.2m).
17-21: WGC Accenture Match Play, Dove Mountain ($8.5m).
March -- 4-7: Honda Classic, Palm Beach Gardens ($5.6m)*. 11-14: WGC CA Championship, Doral ($8.5m). 18-21: Transitions Championship, Innisbrook ($5.4m)*.
April -- 1-4: Shell Houston Open, Redstone ($5,8m). 8-11: US Masters, Augusta National ($7m).
May -- 6-9: The Players, Sawgrass ($9.5m). 20-23: BMW PGA, Wentworth ($9,5m).
June -- 10-13: St Jude Classic, Memphis ($5.6m). 17-20: US Open, Pebble Beach ($7.5m). 24-27: Travelers Championship, River Highlands ($6m) provisional.
July -- 5-6: JP McManus Pro-Am, Adare.
8-10: Irish PGA, The Island (36 holes mooted for Saturday to be confirmed). 15-18: The Open, St Andrews ($7m). 29-August 3: '3' Irish Open, Killarney (€3m).
August -- 5-8: WGC Bridgestone Invitational, Firestone ($8.5M) 12-15: US PGA, Whistling Straits ($7.5m). FedEx Cup play-offs -- 26-29: The Barclays, Ridgewood ($7.5m).
September -- 3-6: Deutsche Bank, TPC Boston ($7.5m). 9-12: BMW Championship, Cog Hill ($7.5m). 23-26: The Tour Championship, East Lake ($7.5m).
October -- 1-3: Ryder Cup, Celtic Manor Resort, City of Newport, Wales.
*Harrington will play either Honda or Transitions, not both.