After balking coming into the arena, Edenvale, ridden by Donald Cheska, won the $25,000 Mercedes Grand Prix of Baltimore today at the Civic Center.

"He was looking around up into the seats," said Cheska, 22, of Milwaukee. "He's very skeptical about going into the ring sometimes."

As Cheska, one of 10 riders in an original field of 18, toured the eight-jump, timed course his horse almost had to jump the electronic timing equipment. But his clocking of 32.05 seconds won the competition watched by 5,000.

"I felt he was very ready," Cheska said of the 11-year-old Irish-bred gelding. "He was amazing. It was his type of jumpoff course."

Today's victory was Cheska's second on the U.S. Grand Prix circuit this year. His first came last month in Newport, R.I., just after switching to a new coach, fellow competitor Michael Matz. "It's largely due to Matz's help that, I feel, I've improved," said Cheska, whose twin brother Richard also competes on the circuit.

Matz, a longtime member of the U.S. Equestrian Team, rode two horses today but failed to qualify for the final. "If he (Matz) was in the jumpoff he'd help me as much as if he wasn't," Cheska said. "He has always given me an honest answer."

Conrad Homfeld of Petersburg, Va., finished second, three-tenths of a second behind on Touch of Class. Third place went to Barney Ward of Brewster, N.Y., on Glandor Akai.

Melanie Smith, last year's winner and present world champion, qualified for the final, but her horse Calypso crashed through the next-to-last jump and finished out of the money.