The NBA Finals and the NHL Stanley Cup Finals jumped out to strong ratings starts in their respective best of seven series.

Thursday’s game one telecast of the Cleveland Cavaliers-Golden State Warriors NBA Finals drew 17.7 million viewers, a record for a Game 1 telecast on ABC, said Nielsen.

The game, in which Golden State won in an overtime thriller, was up 21% from 14.6 million for last year’s San Antonio-Miami game, according to Nielsen.

Game 2 of Cavaliers-Warriors airs Sunday on ABC.

Online, NBA Finals Game 1 on ESPN3 delivered a record 677,669 unique viewers, which is up 117% from Game 1 in 2014.

NBC’s game 1 Chicago Blackhawks-Tampa Bay Lightning Stanley Cup Finals Wednesday averaged 5.5 million viewers, the most watched game 1 telecast ever for NBC and the most watched, non-overtime game 1 telecast in 18 years, according to Nielsen.

The game, won by the Blackhawks, was up 16% compared to last year’s New York Rangers-Los Angeles Kings game 1 telecast.

The Blackhawks and Lightning will hit the ice for game 2 Saturday night on NBC.