Western Conference leaders the Los Angeles Lakers suffered their first defeat in eight games as they were beaten 105-88 by the Memphis Grizzlies on Saturday.
The Lakers had swept aside all in their path since losing to the Houston Rockets on 7 February, including a victory over the Grizzlies at the Staples Center last weekend.
However, they could not maintain that recent form in Memphis, where Ja Morant top-scored for the hosts with 27, while Dillon Brooks and Jonas Valanciunas contributed 24 and 22 respectively.
LeBron James was the Lakers' standout performer with 19 points, 10 assists and eight rebounds.
Meanwhile, Russell Westbrook led the way with a game-high 41 points as the Houston Rockets edged the Boston Celtics 111-110 in overtime.
Westbrook and James Harden combined for 12 rebounds and 13 assists, while Jayson Tatum top-scored for the home side at TD Garden with 32 points to his name.
The result sees Boston, in third, lose ground on the second-placed Toronto Raptors in the Eastern Conference, while the Rockets improved their record to 39-20 and sit fourth in the Western.
The New York Knicks won for the first time in seven games, beating the Chicago Bulls 125-115, while the Miami Heat were 116-113 winners against the Brooklyn Nets.
Elsewhere, the Golden State Warriors overcame the Phoenix Suns 115-99 in Arizona, the Portland Trail Blazers lost 129-117 at the Atlanta Hawks, Orlando Magic suffered a 114-113 defeat to the San Antonio Spurs in Texas and the Indiana Pacers were 113-104 winners on the road against the Cleveland Cavaliers.