That game helped Hayes earn "The Sporting News" College Basketball Player of the Year. One month later on February 10, he grabbed a career-high 37 rebounds in a game against Centenary. In the rematch to the "Game of the Century", Hayes faced Alcindor and UCLA in the 1968 NCAA Men's Division I Basketball Tournament at the Los Angeles Memorial Sports Arena. UCLA coach John Wooden had the Bruins play a 'triangle and two" zone defense with Alcindor playing behind Hayes and Lynn Shackleford fronting him. He was held to 10 points, losing to Alcindor and the Bruins 101-69 in the semi-final game. Hayes led Houston in scoring (1966 27.2 points per game, 1967 28.4, and 1968 36.8). For his college career, Hayes averaged 31.0 points per game and 17.2 rebounds per game. He has the most rebounds in NCAA tournament history at 222. While a student at Houston, Hayes was initiated into the Alpha Nu Omega Chapter of the Iota Phi Theta fraternity alongside fellow future Hall of Famer Calvin Murphy. With his departure from college Hayes was selected as the first overall selection in both the 1968 NBA draft and 1968 ABA draft. He was taken by the San Diego Rockets and the Houston Mavericks, respectively. Hayes joined the NBA with the San Diego Rockets in 1968 and went on to lead the NBA in scoring with 28.4 points per game, averaged 17.1 rebounds per game, and was named to the NBA All-Rookie Team. Hayes' scoring average is the fifth best all-time for a rookie, and he remains the last rookie to lead the NBA in scoring average. He scored a career-high 54 points against the Detroit Pistons on November 11, 1968. In Hayes' second season, he led the NBA in rebounding, becoming the first player other than Bill Russell or Wilt Chamberlain to lead the category since 1957 (Chamberlain was injured during much of the season). In Hayes' third season, 1970–71, he scored a career best 28.7 points per game. In 1971, the Rockets moved to Houston, enabling Hayes to play in the city of his college triumphs. Hayes was acquired by the Baltimore Bullets from the Rockets for Jack Marin on June 23, 1972. He teamed with Hall-Of-Famer Wes Unseld to form a fierce and dominating frontcourt combination. The 18.1 rebounds per game Hayes averaged in 1974 is the third highest rebounding average of any NBA player since Wilt Chamberlain retired in 1973.