For the first time in a quarter-century, Maryland enters the Atlantic Coast Conference Track and Field Championships as an underdog.

North Carolina State is the favorite, with Clemson a reasonably close second, for the three-day event at Charlottesville, which began yesterday with the first half of the decathlon competition. Six finals are scheduled today, with 14 more on the agenda Saturday.

N.C. State has the top-ranked athletes in eight of the 20 events and is especially strong in the sprints and relays.

Clemson, with a large foreign contingent, is the only team other than Maryland to take the title in the last 26 years. The Tigers upset the Terrapins two years ago when Renaldo Nehemiah, the world record holder in the hurdles, left the Maryland team the week of the meet.

"We gave that meet up, but this year we're facing a real dogfight, even if we perform well," said Maryland Coach Stan Pitts. "I hate to say it, but it looks like N.C. State and Clemson, with Virginia and Maryland fighting for third.

"If our guys perform to the upper level, we can win. I don't want to put all the pressure on one guy, but the man who can turn it around for us is Chris Person."

Person last year won the 400-meter intermediate hurdles, placed second in the 110-meter highs and anchored the winning 4x400-meter relay team as Maryland edged N.C. State by 10 1/2 points. He is scheduled for similar duty this time, but has not been running well.

"We haven't had many good workouts because of the cold weather and it seems as if everything that can go wrong, will," Pitts said. "Two weeks ago our best quarter-miler, Darryl Bryant, pulled against Navy and he's out for the year. Last week our bus broke down on the way to Carolina, we sat there two hours and arrived after the meet had started. Maybe we're due for some breaks."

The only Terrapins ranked first in their events are Vince Reilly in the decathlon, Al Baginski in the discus and Dennis Lentz, who shares pole vault honors with North Carolina's Chris Mann.

N.C. State's favored 4x100-meter relay team includes two defensive backs from the football team, Perry Williams and D.D. Hoggard. Williams has been clocked in 20 seconds in a wind-aided 200 meters this spring.

In the decathlon competition yesterday, Willy Pirtle of Virginia, the 1981 runner-up, won three of the five events and took the lead at the halfway point. Pirtle had 3,824 points to 3,807 for Fidelis Obikqwu of North Carolina State, 3,558 for Fred Worthy of Clemson and 3,541 for defending champion Vince Reilly of Maryland.