After the starting upsets of the early rounds, the Wimbledon men's singles final comes down to an appropriate showdown Saturday between the No 1 and No. 2 players in the world: Jimmy Connors vs. defending champion Bjorn Borg.

"There are so many tournaments now, there is no such thing as one match to decide who is No. 1 in the world," says Borj, 21. But there is no doubt that he would most love to beat Connors (television coverage: WRC-TV-4, noon-6:30 p.m.) here, in the oldest and most prestigious tournament in the world.

Borg was distressed last year when most experts rated him No. 2 behind Connors - who had a 3-0 record against the Swede and beat him in the final of the U.S. Open - even though Borg won the World Championship of Tennis (WCT) finals and Wimbledon.

"Every year the player who wins Wimbledon is being ranked No. 1, so I don't understand," he protested.

Connors has a 7-2 lifetime record over Borg, but they have never met on a gross court.

Borg went their first meeting, in the quarterfinals of the Stockholm Open in 1973, and their last, the final of the four-man Pepsi Grand Slam television special at Boca Raton, Fla., in January. Connors won the seven in between.

This year Borg has won five of the 10 tournaments he has played, compiling a 34-4 record. (The final of a tournament in Johannesburg was rained out.)

Connors, 24, who won Wimbledon in 1974 and was runner-up to Arthur Ashe in 1975, has won four of nine tournaments, 33 of 38 matches, in 1977.

Borg, who will play World Team Tennis this year, has won his last three tournament winning streak. Connors has won his last two tournaments, including the WCT finals at Dallas in May. He has won 15 consecutive matches.

Connors, who has been riding around London in a chauffeured limousine that one onlooker described as being "as long and black as John Dillinger's record," has not shifted above cruising speed yet.

He has played only as well as he needed to win, and many suspect there is a championship preformance ready to spring out of the steel racket that he flails ferocity.

Borg, on the other hand, has looked superlative his last two matches. But he may have peaked in his 6-4, 3-6, 6-3, 3-6, 8-6 victory over Vitas Gerulaitis on Thursday, which many consider the best singles match at Wimbledon since Stan Smith. In Borg's Nastase in the 1972 final. In Borg's five-set victory, his advantage in games was only 26-25.

Ross Case and Geoff Masters today won the men's doubles title over fellow Australians John Alexander and Phil Dent, 6-3, 8-9, 6-4.

Case and Masters, who survived four five-setters, thus claimed the title they lost in five excruciating sets to Brian Gottfried and Raul Ramirez last year.

For the third consecutive year, Billie Jean King failed to break the record for career Wimbledon titles in singles, doubles ans mixed doubles.

She needs one more title to eclipse the record of 19 she shares with Elizabeth Ryan, 85, who won 12 doubles and seven mixed crowns between 1914 and 1934. But King and Dent, the U.S. Open mixed doubles champions, were beaten in the semifinals at twilight tonight by South Africans Bob Hewitt and Greer Stevens, 5-7, 6-4, 7-5.

It was te same pair who beat King and Alex Mayer in the second round last year. King tied Ryan's longstanding record when she won her sixth singles title in 1975, but she has been unable to clinch a 10th women's doubles or fifth mixed title.

Betty Stove, the women's singles runner-up, and Frew McMillan reached the final points from 4-5, 0-40 on McMillan's serve in the final set to win, 5-7, 6-4, 12-10.