Just when Texas' title hopes were taking a drenching at the NCAA Track and Field Championships, Eric Metcalf turned the tide tonight. The freshman from O'Connell High School in Arlington, Va., leaped 27 feet one-half inch on his final attempt to win the long jump.

Not only was it a personal best for Metcalf, who marked his 18th birthday in January, but it lifted him within four inches of the world junior record, set by Randy Williams in the 1972 Olympic Games.

Metcalf's breakthrough came at a most opportune time. Just a few minutes earlier, Texas' Patrick Sang, expected to challenge Washington State's Julius Korir for the steeplechase title, had tumbled head first into the water jump halfway through the 3,000-meter event and was fortunate to finish fifth.

Metcalf stood in third place at 26-2 3/4 when he suddenly leaped 8 3/4 inches farther than the career best he had posted only two weeks ago.

"That was phenomenal, really," said Texas Coach Stan Huntsman. "Eric was third at the indoors in 25-10 1/4 and then he missed five weeks of jumping with a heel problem. He won the Penn Relays with 25-9 1/2 and was coming back nicely when he got a bad cold and missed another two weeks."

Metcalf, a tailback and kick returner who is attending Texas on a football scholarship, ranked second among high school athletes indoors last year at 25-5 1/4, but managed only 24-7 outdoors.

Metcalf's effort enabled Texas to take the team lead with one day remaining. The Longhorns collected 36 points to 32 for Washington State. Texas also led the women's race, with 34 to 30 for runner-up Texas Southern.

Korir, the Olympic gold medalist from Kenya, ran the fastest time in the world this year, 8:21.17, to win the steeplechase easily. Sang was running a comfortable fourth when he hooked his foot on the hurdle and went into the water windmill style with about 1,700 meters to go. He was 10th when he rose and needed a gallant effort to close to fifth.

In other highlights tonight, Texas Christian set a collegiate record of 38.46 seconds in the 4x100-meter relay, Danny Harris of Iowa State took his third straight 400-meter hurdles title, Karen Bakewell of Miami (Ohio) set a meet record of 2:00.85 in the women's 800 and Maria Usifo of Nigeria led Texas Southern in a solid bid for women's team honors.

While Washington State and Texas were riding an emotional roller coaster, favored Southern Methodist was disappearing from the title chase.

The Mustangs suffered a three-pronged disaster. Roy Martin, who failed to qualify for the 100-meter final, was a disappointing seventh behind Floyd Heard of Texas A&M in the 200 and anchored SMU's highly regarded 4x100-meter relay team to a fifth-place finish behind TCU. Sven Nylander, the 1983 NCAA winner in the 400-meter hurdles, was fourth behind Harris.

SMU's lone bright spot came from the shot put triumph by Norwegian Lars Nilsen, at 69-7 1/2.

Southwest Conference teams finished 1-2-4-5 in the 4x100. The TCU quartet of Roscoe Tatum, Andrew Smith, Leroy Reid and Greg Scholars handled the baton so smoothly that along with Houston's collegiate and meet records of 38.53, it demolished the stadium record of 38.54 set by the U.S. national team against the Soviet Union in 1982.

Harris, the 1984 Olympic silver medalist behind Edwin Moses, lowered his own meet record by nine-hundredths of a second, to 48.33, as he remained undefeated in collegiate competition.

Bakewell produced a major surprise with her front-running victory in the 800. She disappointed the crowd, as she held off the challenge of Indiana's Tina Parrott, who also went under the meet mark with 2:01.02.

Usifo, a junior from Nigeria, won the 400-meter hurdles in 55.16. Teammate Arnita Epps was fourth in that event, to give Texas Southern 15 points on the 10-8-6-5-4-3-2-1 scoring basis.

Alisa Harvey of Tennessee and Jefferson High in Fairfax, Va., placed eighth in the 800 in 2:04.73. Teresa Allen of Howard was seventh at 20-10 in the long jump, won by Cynthia Henry of Jamaica and Texas-El Paso at 21-5 1/2.