Foaled in Kentucky on February 6, 1987, Dayjur was bred to be exceptionally smart. He was, in fact, descended from two of best stallions ever produced in America. His sire, Danzig, was a son of Northern Dancer, the most influential sire of the twentieth century, and an outstanding stallion in his own right, while his dam, Gold Beauty, was a daughter of Mr. Prospector, another superb stallion, and was named Champion Sprinter of 1982.
Dayjur raced just twice as a juvenile, easily winning the EBF Kennett Maiden Stakes, over 6 furlongs, on his racecourse debut at Newbury in June, 1989 at odds of 8/15, before being beaten half a length by Rushmore, trained by Clive Brittain, in the Manton Rose Bowl Stakes, over the same course and distance the following month, at odds of 8/13. His defeat in the latter contest was blamed on a wind ailment and, after remedial ‘Hobday’ surgery, he reappeared in the European Free Handicap – regarded as a Classic Trial at the time – over 7 furlongs at Newmarket the following April. Despite starting 4/1 favourite, Dayjur was never able to challenge and eventually finished seventh of ten, beaten 6¼ lengths, behind Anshan, who subsequently finished third in the 2,000 Guineas 17 days later.
Dayjur subsequently ran in two minor conditions races, the Headingley Stakes at Nottingham and the HueWilliams Stakes at Newbury, both over 6 furlongs. In the former, he only had to be pushed out in the final furlong to win by 2 lengths, but in the latter, despite running on well in the closing stages, was beaten a head by 20/1 outsider Tod, trained by Jack Berry.
Nevertheless, ten days later, Dayjur tackled the minimum trip, older horses and Pattern company for the first time in the Sears Temple Stakes at Sandown Park. He was, in fact, the only three-year-old in the field, but made all and ran on well to beat the four-year-olds Tigani and Statoblest – who’d finished fourth and third, respectively, in the William Hill Sprint Championship at York the previous August – by 2 lengths and half a length.
Dayjur would go on to win four more Pattern races that season, the King’s Stand Stakes at Royal Ascot, the Nunthorpe Stakes at York, the Ladbroke Sprint Cup at Haydock and the Prix de l’Abbaye de Longchamp, all with plenty in hand, and was unlucky not to win the Breeders’ Cup Sprint at Belmont Park on the final start of his career. In the latter contest, having seemingly taken the measure of the reigning U.S. Champion Sprinter, Safely Held, Dayjur inexplicably fly-jumped shadows twice in the closing stages and was beaten a neck.
Dubbed ‘the fastest horse in the world’ by the Racing Post, Dayjur produced his most memorable performance on British soil in the Nunthorpe Stakes at York on August 23, 1990. Sent off favourite, at 8/11, despite tackling Group One company for the first time, he once again made all the running, as he had at Sandown and Ascot, and stayed on strongly in the final quarter of a mile for a very impressive 4-length win over his old rival Statoblest. In so doing, Dayjur not only set a course record, of 56.16 seconds, which still stands, but also recorded a time figure equivalent to a Timeform Annual Rating of 142. At the end of his career, he had won seven of his 11 races, finished second three times and earned just over £327,000 in prize money.