No one reading the score of Brad Gilbert's 3-6, 6-3, 6-0 semifinal upset of Boris Becker could be more surprised than the winner.

"I'm feeling sky high," said Gilbert, the No. 4 seed and 17th-ranked player in the world, after toppling second-seeded and fourth-ranked Becker yesterday in the Sovran Bank/D.C. National Tennis Classic at Rock Creek Tennis Center. "I felt like I haven't played a good match all week and here I am in the final.

"I feel like anything can happen."

Anything already has happened for Gilbert.

"I've played the top four {ranked players in the world}, what, maybe 50 times. And I've played some great matches and lost," said Gilbert, who beat Jimmy Connors, Anders Jarryd and Stefan Edberg to win at Memphis last year, one of his four tournament titles in 1986.

Perhaps his best remembered victory over one of the top players was a January 1986 upset of John McEnroe in the first round of the Masters. "Then, today, I wasn't playing that well . . . {but} he played horrible."

Gilbert theorized that surprise also was an element in Becker's play: "I think I played so bad at the start that I shocked him, and then he played bad, too."

"The first two sets were just bad tennis," said Becker. "We both had to admit it wasn't the kind of tennis we play. The third set, even though it was love, it was better. We had longer rallies, better shots."

Gilbert showed his frustration with looks of appeal to the sky and hands-on-hips look of disapproval at line judges. After he sent a crosscourt forehand long and lost the opportunity for a break point in the fourth game of the second set, he lectured himself: "Get around it!"

The match's early lethargy might have been another byproduct of surprise.

Gilbert, who before the match expressed wary respect for Becker's serve -- "when he gets tired, he can all of a sudden start bombing in that serve" -- said that despite weeklong observations of Becker staying on the base line, he expected some serve-and-volley play from his opponent.

But Becker didn't bomb in the serve and he didn't come in. He said it was because a week's worth of aches and pains after last weekend's strenuous Davis Cup play left him trying to "save everything I have and hope the other guy would miss it."

With Becker staying back, Gilbert saw a big opening at the net.

"After the first set, I started coming in a lot more. . . . I thought I might as well get into the point," said Gilbert.

However, in the sixth game of the second set, it was a forehand passing shot that got him double break point and finished the game when his short backhand drew Becker in and Becker's forehand volley went wide. Becker broke back in the next game, but Gilbert made it three in a row and went ahead, 5-3, with a break in the next game.

Gilbert reached his first set point with a service winner, then Becker fought back through two deuces before Gilbert closed the set out with two strong serve-and-volley points.

Said Gilbert: "I felt like, all of a sudden, when I broke him at 5-3 and then I touched out that game to take the set, I think he suddenly got tired."

That was fine with Gilbert. "Sometimes you need a little luck," he said. "I felt like today I got a little luck."

Luck and a litte more will be needed to give him his first title of 1987 when he plays No. 1 Ivan Lendl, a straight-sets winner over No. 3 Jimmy Connors, in the final tonight. "I'm definitely going to have to play a little better," he said.

Gilbert is hoping those elements might combine to give him another surprise in this tournament, his first title since last October when he won in Vienna over another player with a history of winning here -- Karel Novacek, who earned his only title here a year ago.