Khris Middleton found the basket with 0.5 seconds left in overtime as the Milwaukee Bucks drew first blood in their play-off match-up against the Miami Heat.
Middleton top scored for the Bucks with 27 and his 19-foot shot sealed a 109-107 win against the sixth seed.
Jimmy Butler, who had 17 points, had earlier denied the Bucks when he forced overtime with a buzzer-beating lay-up to make it 99-99 and the Heat's Goran Dragic made it 107-107 with 20.6 seconds to go before the Bucks prevailed.
Also in the Eastern Conference, the Brooklyn Nets are 1-0 up in their series after a 104-93 victory over the Boston Celtics.
Brooklyn's big three – Kevin Durant, Kyrie Irving and James Harden – scored 82 between them, with Durant top scoring with 32.
Luka Doncic scored 31 points as the Los Angeles Clippers were downed 113-102 by the Dallas Mavericks and the Portland Trail Blazers saw off the Denver Nuggets 123-109.