Endelman joined the Columbia tennis ranks for the 1984 season as a budding star. The top ranked junior (18 & under) in the East, Endelman came to Morningside Heights via nearby Roslyn, N.Y. on Long Island. At Roslyn High, Endelman was an all-state performer all four years, while serving as a two-time captain.
He wasted little time acclimating to the collegiate game, helping Columbia go undefeated during the 1984 regular season. An overall 17-0 mark and 9-0 mark gave Columbia the first of two Eastern Intercollegiate Tennis Association and Ivy League titles it would win during Endelman's career, as well as advancing the Lions to the NCAA Championships. Considered a serve and volley specialist, Endelman closed out his rookie season winning nine of his final 10 matches, finishing with a 12-6 singles mark at No. 3. An impressive 14-4 mark in doubles with teammate Gary Jacobs earned him All-Ivy League recognition.
Endelman's success on the court continued over the next two seasons, as he lost just two singles matches while winning 30. He picked up another All-Ivy League doubles honor as a sophomore and moved into a captain role as a junior and senior. The 1985 and 1986 teams remained top contenders for the EITA and Ivy League championships, but came up just short of Harvard each year.
Returning for his senior campaign, Endelman developed into a quality leader that had a winning spirit. Those characteristics guided the Lions to a 15-4 overall record, including an unblemished 9-0 mark in EITA matches to capture the second conference title and second appearance in the NCAA Championships during Endelman's four-year career. The Lions gained national prominence, rising to as high as No. 17 in the nation during the season. Individually, Endelman put together a 13-2 singles mark to finish his career with a 55-10 record. Paired with Keith Thomas in doubles, the duo went 11-2 and 6-0 in conference matches, earning Endelman All-Ivy League doubles accolades for the third time in his career.
Upon graduating from Columbia, Endelman turned to the ATP Tour, competing in the main draws of both the U.S. Open and Wimbledon. He rose as high as 183 in the world in doubles. He returned to Columbia as the interim head coach of the women's squad in January of 1990 with interim tag being removed following a 6-6 record that spring. At 24 years old, he was the youngest Division I head coach. He coached the next two seasons, leading Columbia to a 25-24 record before stepping away from coaching to attend law school and enter the world of business.
Ever the Columbia man, Endelman returned in August of 2010 as the associate head coach alongside the man who recruited him, Bid Goswami. In his four seasons, the Lions have went 62-29 and 19-9 in the Ivy League, highlighted by the 2014 squad's historic campaign that included the program's 11th conference title, a trip to the NCAA Championships and a No. 16 national ranking. In 2013, Endelman was recognized by the ITA as the Northeast Region Assistant Coach of the Year for his devotion to Columbia tennis and the game itself
