Todd Minikus of Lake Forest, Ill., guided Thrilling tightly around every turn to win the first International Open Jumper event at the Washington International Horse Show at Capital Centre last night.

Thrilling was quick and concise and cleanly jumped the 10-fence course in 49.35 seconds to win the $7,500 event and Eisenhower Trophy.

Of the 29 entries, 10 finished the round cleanly.

Donald Cheska of Racine, Wis., and Dury Lad were runners-up in 52.99. Cheska's twin brother, Richard, riding Mill Haze, was third in 55.49.

Five international team members also finished the round without fault.

The U.S. team's Alice Debany, the top international rider in the event, and The Natural took an early lead with a clean effort in 56.5.

The other USET members, Tony Font on Lego, David Raposa on Seven Wonder and Hap Hansen on Zulu, each knocked down one fence for four faults.

Beth Underhill (61.57) rode Monopoly for the Canadian team and finished fifth, followed by teammate Mac Cone (61.54) on Pessimist.

Britain's Tim Grubb (61.75) rode Ever for seventh place.

The USET and Canada took an early lead in the team standings with three points each. Minikus is the leading rider with seven points.

The one-round event was scored according to the number of faults, or fences knocked down. Time taken to complete the course was used to break ties between competitors with clear rounds.

In morning competition, Kirin, owned by Thom and Adele Mitchell of Franklin, Tenn., and ridden by Patty Stovel, gained 10 points towards the International Hunter Futurity Grand Championship with a first-place finish in an over-fences class. In addition to the six points earned in two classes Monday, Kirin became one of the top competitors for the trophy in the hunter event.

Outer Banks was second in the event, which tries to encourage the breeding of quality show ring hunters. Ridden by Olin Armstrong, Outer Banks gained six points for an overall total of nine. Everlero, ridden by Terry Brown, was awarded third for three points and a total of nine.

Conversation Piece, owned and ridden by Shelly Stiegler, continued to top the field in the first-year green hunter division, finishing first in the hunter stake and seventh in an under saddle class. Conversation Piece finished first and second in two classes Monday.RESULTS

$7,500 International Open Jumper (rider, horse, time): Todd Minikus, Thrilling, 49.35 seconds; Donald Cheska, Dury Lad, 52.9; Richard Cheska, Mill Haze, 55.49; Alice Debany, The Natural, 56.50; Beth Underhill, Monopoly, 61.37; Mac Cone, Pessimist, 61.54; Tim Grubb, Ever, 61.75; Michael Dorman, Cool Dawn, 62.17.

International Hunter Futurity, Over Fences (horse, owner, rider): Kirin, Thom & Adele Mitchell, Patty Stovel; Outer Banks, Mr. & Mrs. David Ashcom, Olin Armstrong; Everlero, Showcase Ltd., Terry Brown.

International Hunter Futurity, Breeding Challenge Yearling (horse, owner): Send For The Captain, Sunfield; Trump, Warioto Farm Inc.; Classy Fox, Karen H. Hall; Made To Order, Gail Bialek.

2-Year-Old: Nechac, Nokomis Farm; Chain Of Pearls, Stoney Point Farm; Blue Run, Nokomis Farm; Fleetwood Thom, John E. Davis; Special Edition, Gail Bialek.

3-Year-Old: Thom Terrific, Marianne Wheliss; Star Edition, Cyndi Elmore; Just In Texas, Gail Bialek, Pine Meadow Farm and Sandy & Ed Minchin.

First-year Green Hunter: Central Station, Fields And Fences, Tim Goguen; Kawahma, Alex Gilbert, Stacia Klein; For Many Reasons, Cismont Manor Farm, Tommy Serio.

First-year Green Hunter Stake: Conversation Piece, Shelly Stiegler; Ozzie, William C. Rappolt, Louise Serio; For Many Reasons.

Second-year Green Hunter: Two Of Hearts, Sallie Schwartz/Jackie Schwartz, Jenny Karazissis; Meant To Be, Leann Morris/Don Stewart Jr., Scott Hofstetter; Toast Of The Town, Laurie Lafavers, Patrick Rice.

Second-year Green Hunter Stake: Meant To Be; Memphis, Barbara Trueman/Truesports Inc., Leslie Lenehan; Lucullas, Linda Robinson/The Lake Hill Farm, Charlie Weaver.