To be continued. . . .

LA JOLLA -- He did it again, almost on command, as Rocco Mediate’s heart, and the sun, sank.

Tiger Woods, who before the 108th U.S. Open had not walked 18 holes since left knee surgery on April 15, is going to walk at least 18 more.

He’s going from a long layoff to a long playoff.

“I was planning on going to Mexico,” Woods said when asked where he was originally headed today.

Not now.

Woods slithered a 12-foot birdie putt into the right side of the cup at No. 18 to pull even with Mediate on Sunday’s 72nd hole and force one extra day of adrenaline at Torrey Pines.

Woods and Mediate finished one-under 283 overall.

Lee Westwood’s two-over-par 73 left him one shot out of the party and sent him home at even-par 284. Robert Karlsson and D.J. Trahan finished three shots back at two-over 286. They are all footnotes now.

Woods had lost the one-shot lead he took into Sunday, struggled to a two-over 72, struggled with his driver and with his putting.

But he made the putt he had to make when he had to make it.

“I made him do something amazing today, which is amazing,” Mediate said of the putt. “He does it all the time . . . but I made him do that.”

The U.S. Open is the only one of the four majors that requires an extra 18 holes to determine its champion, like it or not.

“I have nothing left right now,” Mediate confessed. “I’m toast. It was the most amazing day of golf I’ve ever experienced.”

So is he up for another one?

“It’s going to be unbelievable,” he said.

It will be the first U.S. Open playoff since 2001 at Southern Hills, when Retief Goosen defeated Mark Brooks on a Monday in Oklahoma.

Never mind that Woods vs. Mediate sets up like Ali vs. Wepner.

Woods is 32 years old to Mediate’s 45. Woods has won 13 major championships to Mediate’s none. Woods has 64 PGA tour victories to Mediate’s five.

Upon arrival at Torrey Pines, Mediate had one top-10 finish this year and had missed eight of the first 10 cuts on tour this season.

Woods had nine exemptions qualifying him for the U.S. Open. Mediate earned his way in at a sectional qualifier in Columbus, Ohio.

But Mediate is going to show up.

“He wants to kill me, I want to kill him, that’s just how it is,” Mediate said.

The scene at Sunday’s par-five 18th, playing at 527 yards, was tee-box tense.

Mediate was restless in the scorer’s tent at one under after he finished his round of even-par 71.

Woods and Westwood were one group back, both one shot back.

You could sense the playoff coming when Mediate made par five on the finishing hole when birdie would have forced Woods and Westwood to make eagle.

Mediate’s hopes were buoyed, though, when Westwood and Woods hit their drives into bunkers, forcing lay-ups on a hole that was reachable in two.

Westwood found the fairway fine, but Woods’ bunker shot went into the rough.

Both players nailed the green with their third shots, within striking distance of the cup.

Westwood putted first, from about 20 feet, but his chance to tie slid right of the cup.

He was trying to become the first Englishman to win the U.S. Open in 38 years.

“It’s sickening not to be in the playoff tomorrow,” Westwood said.

Woods seized his chance with his usual laser-beam stare.

Mediate was holed out and holed up inside, adjacent the 18th grandstand, waiting to see whether he was going to get to hoist a trophy or set his alarm clock.

Woods made the putt, of course.

It was nothing like the Tiger Woods of Saturday who dazzled watchers when he made back-nine eagles on No. 13 and No. 18 and a chip-in birdie on No. 17.

Woods, on Sunday, seemed on the verge of losing a major for the first time when he held the third-round lead.

He started double-bogey/bogey and had to fight to get his lead back.

He was two under, with a one-shot lead, when he birdied the par-three 11th, but he gave a shot back on the par-five 15th when he hooked a three-wood into the canyon and had to take a one-stroke penalty that lead to a bogey six.

“That was just a terrible shot,” Woods said.

He also made an interesting decision to lay-up at No. 14, a par-four that had been shortened to 267 yards. Woods said he didn’t have the right shot for the distance.

“I’m caught right in between clubs,” he said.

Woods made par on a hole that yielded 26 Sunday birdies.

One shot behind with one to go, Woods said he approached No. 18 with the killer’s instinct.

His thought was “eagle to win,” but a trip to the bunker changed those plans. He then just wanted get close enough to the pin to “at least give myself a putt at it.”

Which he did.

One question leading into the playoff might be: what will break down first over 18 holes: Mediate or Woods’ knee?

Woods has been hobbling all week, wincing after powerful swings, and he’s now on course to play 90 holes in five days.

Was the knee better or worse?

“Not better,” Woods said.

What did the doctor say about your knee?

“Don’t play golf,” Woods said.

Instead, Woods has opted for more, pitted against a friend, but a decided underdog, in quest of his 14th major championship.

It’s Tiger vs. Rocco.

“I’m playing against a monster,” Mediate conceded.

He wasn’t talking about the course.

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chris.dufresne@latimes.com

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Today’s 18-hole playoff match: Tiger Woods vs. Rocco Mediate, 9-11 a.m. (ESPN), 11 a.m. (Ch. 4)

(BEGIN TEXT OF INFOBOX)

Tale of the tape

How Tiger Woods and Rocco Mediate match up for the 33rd playoff in U.S. Open history.

WOODS/MEDIATE

*--* 32 Age 45 1996 Turned pro 1985 $81 mil. Career earnings $13.7 mil. 1 World ranking 158 64 PGA Tour wins 5 13 Majors won 0 10-1 PGA playoff record 2-0 *--*

Last PGA victory for Woods: Arnold Palmer Invitational (March 16, 2008).

Last PGA victory for Mediate: Greater Greensboro (April 28, 2002).

Sunday’s final round: Mediate and Woods both finished at one-under 283, the first under-par score in the Open in four years. Mediate shot a final round 71 to a 73 for Woods.

Last three U.S. Open playoffs:

* 2001 -- Retief Goosen (70) d. Mark Brooks (72) at Tulsa, Okla.

* 1994 -- Ernie Els (74) d. Loren Roberts (74) and Colin Montgomerie (78) at Oakmont, Pa. (Els d. Roberts on second sudden-death hole).

* 1991 -- Payne Stewart (75) d. Scott Simpson (77) at Chaska, Minn.