Sue Barker, a 20-year-old Englishwoman whose sore right shoulder was not as bad as Martina Navratilova's ailing left one, upset the expatriate Czech today and earned a spot in the Sunday final of the $10,000 Virginia Slims championship.

Barker, who triumphed, 7-5, 6-4, met Chris Evert, who breezed into the Madison Square Garden final as surely as summer follows spring with a 6-1, 6-1 victory over Rosemary [TEXT OMITTED FROM SOURCE]

At stake Sunday is the $50,000 first prize and the first leg (Wimbledon and the U.S. Open are the others) of a modern Triple Crown of women's tennis.

Evert has been in the title match each year since this nouvelle-riche championship began in 1972, winning that year and in 1972 and 1975, losing a magnificent final to Evonne Goolagong last year in Los Angeles.

Navratilova, runner-up in 1975, and Barker have been the non-pereil Evert's chief rivals on this year's Slims tour.

Evert won five events; Navratilova, four (including Washington, over Evert in the first tournament of the year); Barker, two. They finished one-two-three in the final standings.

Barker is hoping to end a long winter of frustration against Evert, who has won all three times they've played this year. Barker is 0-11 against Evert lifetime.

Barker is in the proper frame of mind, brimming with confidence after snapping the aggressive Narvratilova, who had beaten her in the finals of tournaments at Houston, Minneapolis and Detroit.

At the beginning of the Slims circuit, Barker made herself a modest proposal: She wanted to win one tournament. She has elevated her aspirations since.

She will be a decided underdog against Evert, who said she "played just about as well as I can" in disposing of Casals in a mere 48 minutes.

Barker likes to stay in the back court, thumping her atomic forehand, challenging net-rushers like Navratilova. She is less comfortable against baseline strokers, of whom Evert is the most unerring and unflappable of them all.

[TEXT OMITTED FROM SOURCE] marigold-colored round-robin groups, the women with the best record in the Gold Group facing the best of the Orange for the title.

As it turned out, today's final session of the three-day round-robin turned out to the like regular semifinals. Evert, Casals, Barker and Navratilova all came in with 2-0 records, so the winner of their showdowns knew they were in the final.

The two other matches decided only the fifth through eighth places. Betty Stove defeated Kristien Shaw, 61- 64, and Virginia Wade outlasted Mima Jausovec, 6-7, 6-3, 6-4, in a thriller that delighted the crowd of 8,462.

The final standings in the Gold Group were Evert (3-0), Casals (2-1), Wade (1-2), and Jausovec (0-3). In the Orange it was Barker (30), Navratilova (2-1), Stove (1-2) and Shaw (0-3).

Wade and Stove earned $11,000 apiece; Jausovec and Shaw, $9,000. Navratilova and Casals play for third place Sunday, the winner getting $16,000, the loser, $14,000. The loser of the Ever-Barker match collects $30,000.

Barker, a slip of a lass whose gahe is built around a heavyweight foehand, won today because she has improved her weaker side remarkably.

The most critical points she won with her backhand, which she was hitting well both down-the-line and cross court. She formerly sliced almost everything on that side, but now she hits flat or even with a hint of topspin.

She killed Navratilova with backhand passing shots and service returns, including several beauties that she crackled short and cross-court at a sharp angle.

She also hit most of the time to Navratilova's backhand, always her weaker side and obviously inhibited today by tendinitis in her left shoulder.

Most of the time Martina was reduced to grabbing the racket with both hands on the backhand because she could not get her shoulder up to the ball. Through the middle of the match, it was painful to watch. She was so tentative she seemed like a tin woman, her shoulder crying out for oil.

Navratilova its loose in her last two service games, putting nine of none first serves in and winning eight so those points, but by that time Barker hand pulled out to a lead she was not about to relinquish.

She had held serve for a 4-2 lead in the second set, ending a string so five consecutive service breaks in which she choked more on her forehand than her suddenly forceful backhand.

Baker sewed out the match at 30, appropriately whacking three perfect backhand cross-court winners.

Barker served well - the serve is usually the other most vulnerable part of her game - moving the ball around instead of succumbing to the temptation of going for Navratilova's wounded backhand.

She served three aces, and was not noticeably bothered by her own shoulder miseries, a pulled muscle for which she has been taking the anti-inflammatory Butozoiidin the last two weeks.

Evert did what she always does well - hammer away with ground strokes that are incredible in the consistency of their depth and accuracy - better than even she usually does.

"She didn't let me get into the net, and I couldn't keep up with her from the baseline. She just killed me. I won only two game, and I didn't think I was playing badly," said Casals, who must have like a cucumber going one-on-one with one of those vegetable slicers the fast-talking man peddles between reels of the late show.

The only time Evert seemed ruffled was after the match; when a reported asked her if she were having a romance with actor Burt Reynolds, whom she has dated from time to time, including this week.

"What do you mean by a romance?" Chris retorted, coming as close as she ever does to bristling she paused, collecting her nearly unassailable composure, and added. "I really don't think that has anything to do with the match."