Answer by taking a quote from the following article:

Affirmed (February 21, 1975 - January 12, 2001) was an American Thoroughbred racehorse who was the eleventh winner of the United States Triple Crown of Thoroughbred Racing. Affirmed was also known for his famous rivalry with Alydar, whom he met ten times, including in all three Triple Crown races. Affirmed was the last horse to win the Triple Crown for a 37-year period, which was ended in 2015 by American Pharoah. Affirmed won fourteen Grade

As a two-year-old, Affirmed won seven of his nine starts, with two placings, for earnings of $343,477 under regular rider Steve Cauthen, then a teenager. Notably, six of those starts were against his rival, Calumet Farm's Alydar, with Affirmed winning four and Alydar winning two.  Affirmed won his first start in a maiden special weight race at Belmont Park on May 24, 1977. He followed up with a win in the Youthful Stakes on June 15 where he defeated Alydar by eight lengths. On July 6 in the Great American Stakes, Alydar evened the score with a  3 1/2 length win after mounting a powerful stretch drive.  Affirmed was then shipped across country to Hollywood Park, where he won the Hollywood Juvenile Championship Stakes on July 23. He then shipped back to New York where he won the Sanford Stakes at Saratoga on August 17 by  2 1/2 lengths over the previously undefeated Tilt Up. In his next start on August 27 in the Hopeful Stakes, his main rival was Alydar, who was the even money favorite after winning four straight races. Affirmed stalked the early pace set by Tilt Up with Alydar in close contention. Around the far turn, Affirmed moved to the lead with Alydar closing ground on the outside. In mid-stretch, Alydar had closed to within a head but Affirmed pulled away in the final sixteenth of a mile to win by half a length. His time of 1:15 2/5 for  6 1/2 furlongs was a new stakes record.  The two horses again faced off in the Belmont Futurity on September 10, with Affirmed going off as the narrow favorite. After a good start, Affirmed settled into second place behind longshot Rough Sea, while Alydar overcame a bad start to move into third place down the backstretch. Rounding into the stretch, Affirmed moved to the lead. Alydar responded and the two horses dueled head-to-head for the final furlong. Alydar appeared to be in the lead for much of the stretch drive before Affirmed rallied in the final stride to win by a nose. "He never gave up," said Cauthen, "even when he was headed."  Alydar turned the tables in the Champagne Stakes on October 15, sweeping by Affirmed in the stretch to win by  1 1/4 lengths. The two faced off again in the Laurel Futurity on October 29, then one of the most prestigious races for two-year-olds in the country, with Affirmed winning by a neck. With his 4-2 margin in the series against Alydar, Affirmed was named the 1977 American Champion Two-Year-Old Colt.

Did he have any notable losses?
Alydar turned the tables in the Champagne Stakes on October 15, sweeping by Affirmed in the stretch to win by  1 1/4 lengths.