By Jill Serjeant and Lisa Richwine | NEW YORK/LOS ANGELES
The first presidential debate between Democrat Hillary Clinton and Republican Donald Trump drew 84 million U.S. television viewers, a record for such an event and numbers rarely seen on TV in the age of digital streaming and social media.

The audience for the Monday night face-off beat the 1980 record of 80.6 million set by the Jimmy Carter-Ronald Reagan presidential debate, when viewers had far fewer entertainment options. But it fell short of the 100 million viewers some analysts had predicted.(from Reuters)

presidential debate　 大統領候補討論会
showdown　 対決
1《口語》 (どたん場の)対決.

when it comes to a showdown いよいよという時には.
2【トランプ】 (ポーカーで)ショーダウン 《持ち札を全部見せること》.
break a (previous) record　 (これまでの)記録を更新する
(from研究社 新英和中辞典)