ORLANDO, Fla. — Even after eight decades of golf, Arnold Palmer is vulnerable to a few surprises.

In this case, both occurred on the same day.

He watched the final round of the Tour Championship, where Tiger Woods started two shots out of the lead and didn’t make a birdie until the 15th hole. By then, Phil Mickelson blew past everyone and won by three shots.

“I was a little surprised at Tiger,” Palmer said Tuesday at his Bay Hill Club. “If you just watch him like I do — and I’ve watched him since he was a little guy — just the way he walks, the way he holds himself, it amazed me he didn’t win. That was my reaction.”

And then came a bigger surprise.

Did he ever imagine seeing two fierce rivals posing on the 18th green while holding their own trophy?

Palmer threw his head back and laughed.

“No, but that’s good,” he said. “I did think about that. I just didn’t put it that context.”

Sunday at East Lake presented a bizarre scene, for sure, when Mickelson rallied to win the Tour Championship and Woods did enough on the back nine to capture the FedEx Cup. The PGA Tour could not have asked for a better finish to its FedEx Cup. Golf is at its most interesting when Woods and Mickelson are on top of their games.

The question is how long this will last.

The next time Woods and Mickelson play against each other — assuming they aren’t partners in the Presidents Cup — is scheduled to be the HSBC Championship in Shanghai the first week of November.

The better barometer will be in 2010.

The way he won and the player he beat must have made Mickelson wish that next year started next week. He had been hitting the ball well enough to contend just about every week. His driving — higher launch, less spin, straighter than ever — was superb at East Lake.

The problem was his putting, which was so bad that Mickelson asked his caddie for suggestions. Jim “Bones” MacKay jumped at the chance to help, and spent the Monday after the BMW Championship searching for Dave Stockton’s phone number.

“Bones came up with the idea,” Mickelson said. “I said, ’Bones, for two years I’ve been kind of floundering here, not having the right direction. I want you to think about it.’ He came back the next day and he said, ’I think you should call Dave Stockton.”’

Mickelson and Stockton hooked up in San Diego, and Stockton encouraged him to return to his putting style of old — a forward press with his hands, which Mickelson had been doing since he was a kid. The move felt natural, and the results were astounding. He one-putted 36 times over 72 holes at East Lake.

“I feel like I have some direction now on where I want to go with my putter,” Mickelson said. “I felt like I’ve been hitting it this well for quite some time since working with Butch (Harmon), and yet I have not had the results. To be able to put it all together from tee-to-green, as well as on the green, feels great.”

He looked so good that NBC Sports analyst Johnny Miller suggested Mickelson could win PGA Tour player of the year.

Mickelson is talented enough to do that.

So, too, is the guy he has been trying to chase for the better part of a dozen years.

Even a player of Mickelson’s caliber — 37 career victories on the PGA Tour and three majors — still needs more than one tournament to show that he is up to the challenge. Because what the last decade has shown is that when Mickelson appears ready to challenge, Woods always seems to have an answer.

Go back to 1998.

One year after Woods’ established himself at No. 1 with a 12-shot win at the Masters among his four victories, Mickelson won the season-opening Mercedes Championship with a strong statement. After hearing the roar for Woods’ eagle during a Sunday charge, Mickelson fired off four birdies over the next five holes and went on to win at La Costa.

He didn’t win again for seven months. He didn’t win a major for six more years.

Some other examples:

— Mickelson won consecutive events on the West Coast in 2005 and was atop the leaderboard for 10 consecutive rounds in stroke play until Woods beat him in a duel at Doral. Mickelson didn’t win again until the PGA Championship five months later.

— Mickelson was one hole away from joining Woods and Ben Hogan as the only players to win three straight majors in the modern era until he took double bogey on the 18th hole at Winged Foot and tied for second in the 2006 U.S. Open. He didn’t seriously contend in another major for two years.

— Playing with Woods for third time in four days, Mickelson buried him on the front nine of the TPC Boston and shot 66 for a two-shot victory at the 2007 Deutsche Bank Championship. That gave Mickelson the lead in the FedEx Cup standings, but he took the next week off. Woods answered by winning the final two playoff events and the FedEx Cup.

So what will this Tour Championship victory over Woods do for Mickelson?

Lefty turns 40 in June, which could give him an even greater sense of urgency. Then again, Woods has a say in this rivalry, too.

“Certainly, I would love to go at it again with him,” Woods said.

Most everyone would love to see it.

Perhaps the Tour Championship was preview for what could be a special year in 2010.

Or maybe it was a rerun.