David Moorcroft, Britain's new running hero, broke away from a field of world-class distance men tonight to win the second-fastest 3,000 meter race in history, 7 minutes 32.79 seconds.

Moorcroft, who set the world record at 5,000 meters in Oslo earlier this month, outpaced such celebrated running names as Britain's Steve Ovett and American Steve Scott, who finished 10th and fifth, respectively.

Tonight's race at London's Crystal Palace was originally intended as a match between Ovett and Britain's other most famous middle distance runner, Sebastian Coe. But an injury to Coe forced him to withdraw. Organizers then amassed a field that brought many of the world's best runners together.

Kenya's Henry Rono, back in the pack tonight, holds the record of 7:32.1. He had come under pressure from the Kenyan Athletic Federation which almost withdrew him from the meet because of his refusal to join an African team in the United States recently.

Second in the race was Sydney Maree, a South African who now lives in the United States and attends Villanova University. He stayed close to Moorcroft throughout the race and passed him on the last backstretch. But Moorcroft, obviously still riding high from his record pace performance in Norway, retook the lead coming off the final turn and won by about four yards.

The most disappointing performance of the evening must surely have been Ovett's. He has been slowly recovering from an injury last winter and dropped out of a race in Paris last week complaining of stomach pains. He was not in good form tonight and left the track hanging his head.

It is not likely that Ovett will have a chance to meet Coe in two races later this summer and fall that were intended to decide the issue of which was Britain's fastest middle-distance runner.

For the moment at least, that distinction belongs to Moorcroft. He is a widely respected but previously little-known competitor who was champion in the Commonwealth Games and European Cup but never considered a prime contender for world record marks.

Following behind Moorcroft and Maree tonight was John Walker of New Zealand, the 1975 world record holder in the 3,000 meters, who is running faster than he was six years ago. Other celebrated names such as West Germany's Thomas Wessinghage, Kenya's Mike Boit and Peter Koech finished far back.

The time for the race never broke through record pace. The first lap was clocked at 61.8 seconds. The third lap at 3.03 was right on the record mark but by the sixth lap of the 7 1/2-lap race the runners were falling short of the top mark.