Caucasus made a successful racecourse debut in a maiden race over ten furlongs at Phoenix Park Racecourse and followed up in a handicap over one and a half miles at the Curragh. In June he was sent to Northeren Ireland for the Ulster Derby at Down Royal and won his third consecutive start. In August he was sent to England for the March Stakes over fourteen furlongs at Goodwood Racecourse. He started odds-on favourite but after being retrained towards the rear of the field he failed to overhaul Whip It Quick and finished second, beaten half a length by the winner. On 20 September Caucasus equipped with blinkers when he was moved up in class for the Group 1 Irish St Leger over fourteen furlongs at the Curragh. Ridden by Lester Piggott he started the 3/1 second favourite behind Nuthatch while the other eleven runners included Shantallah, Music Ville, Sir Daniel and Quiet Fling. Caucasus took the lead soon after the start and maintained his advantage into the straight where Quiet Fling emerged as his only serious challenger. Quiet Fling went to the front approaching the final furlong but Caucasus rallied to regain the lead and drew away in the closing stages to win by two lengths. At the end of the season the independent Timeform organisation gave Caucasus a rating of 127, making him ten pounds inferior to their Horse of the YearGrundy.
1976: four-year-old season
Before the start of the 1976 season Caucasus was sold and returned to the United States to be trained by Charles E. Whittingham. He was mainly campaigned in California, with six of his eight races taking place at Hollywood Park Racetrack. In May he was beaten in two allowance races but then won the South Bay Handicap and finished second to Dahlia in the Grade IHollywood Invitational Handicap. He returned to the track in July to finish third to King Pellinore the Grade I American Handicap and then won the Grade I Sunset Handicap, reversing the form with King Pellinore. After a two month break he was shipped to the East coast for two races at Belmont Park. He won the Grade II Manhattan Handicap but then ran unplaced in the Man o' War Stakes The New York Times described Caucasus as "Hollywood Park's best grass horse in 1976".
1977: five-year-old season
Caucasus showed his best form of 1977 at Santa Anita Park in March when he followed up a win in the Grade III Arcadia Handicap with a victory in the Grade I San Luis Rey Handicap eleven days later. He failed to win again that year but posted some solid efforts in defeat, finishing second in the Hollywood Invitational and third in both the San Juan Capistrano Handicap and the Hollywood Gold Cup.