Polls show Mr Trump is losing in key battleground states after facing a slew of sexual assault allegations.
据民调显示,由于川普所面临一系列性侵指控的原因,他在一些主要的州的情形非常不利。
But Mrs Clinton remains unpopular with many US voters and has faced more bad headlines about her use of a private email server.
但是希拉里也不受很多美国选民的待见,并且在使用私人邮件服务器丑闻一事上泥足深陷,频频被人批判一番。
Most Americans will cast their votes on 8 November.
大多数美国人都会在11月8日那天投出自己的一票。
Millions are expected to tune into the third and final debate at the University of Nevada, Las Vegas which gets under way at 21:00 EDT (01:00 GMT) and will be moderated by Fox News journalist Chris Wallace.
数以百万计的人将会收看于美国东部时间21点(中央时区凌晨1点)在拉斯维加斯内华达大学举行的第三场(也是最后一场)总统辩论,届时福克斯新闻记者克莉丝·华莱士将会担任主持。
The two candidates will discuss six topics: national debt and health and social benefits, immigration, the economy, the Supreme Court, foreign flashpoints and their fitness to be president.
川普和希拉里将会讨论6个方面的议题:国债与健康和社会福利问题、移民问题、经济问题、法院问题、外交热点问题、以及各自阐述为何自己适合当总统。
Mr Trump has faced damaging fallout after a video emerged of him making obscene comments about groping women, with senior Republicans deserting him.
川普之前曾被曝出一份视频,他在视频中对如何抚摸猥亵女性讲了一些下流话,他也因此遭到了毁灭性的打击,共和党高层也抛弃了他。
In recent days he has railed against the election process itself, warning the vote is "absolutely rigged" with "large-scale voter fraud" taking place.
最近几天,川普对此次选举过程本身也进行了谴责,警告说正在发生“大规模的选举舞弊”,此次选举“绝对被操纵了”。
His remarks prompted a scathing response from President Barack Obama, who said the Republican challenger should "stop whining".
川普的言论引起了总统奥巴马的严厉回应,后者告诫川普应当“别再牢骚满腹”。
Mr Trump has invited President Obama’s estranged half-brother, Malik Obama - one of his supporters - as a guest.
奥巴马有一个久未联系的同父异母兄弟马利克·奥巴马,此人是川普的支持者,而川普已经对他发出了邀请。
He also invited Patricia Smith, whose son was killed in an attack on the US diplomatic mission in Benghazi, Libya, in 2012, while Mrs Clinton was US secretary of state.
川普同样邀请了帕特丽夏·史密斯,后者的儿子于2012年在利比亚班加西执行外交任务时死于一场袭击,当时希拉里担任美国国务卿。
In contrast to Mr Trump, Mrs Clinton has kept a low profile ahead of the debate to prepare for the showdown.
与川普的大张旗鼓相比,希拉里则非常低调地在为最后的决胜之局做准备。
Her spokesman said the Democratic nominee was ready for whatever "scorched-earth" tactics her rival might try.
据希拉里的发言人表示,她已经做好了准备,无论川普到时会使用何种“焦土战术”。
Mrs Clinton is likely to face questions about a batch of hacked emails from the account of her campaign boss, released by Wikileaks, that her rival has seized on.
之前黑客攻击了希拉里竞选经理的邮箱账户,一批邮件被盗,维基解密公布了这些邮件,目前已经被川普所掌握,而在此次的辩论中,希拉里将面临关于这些邮件的问询。
Before the last debate, Mr Trump appeared at a news conference with women who accused Bill Clinton of sexual misconduct. Since then he has suggested Mrs Clinton took performance-enhancing drugs ahead of that meeting.
在最后一次辩论开始前,川普出现在了一场新闻发布会中,与他同时出现的还有一名女子,该名女子指责比尔·克林顿有过猥亵行为。自那以后,川普还建议希拉里在辩论前吃一些性能增强药物。
But Mrs Clinton’s campaign has signalled their candidate will try to focus on policy.
但是希拉里阵营则透露说,希拉里将会专注于政策方面。
Among her guests, Mrs Clinton is bringing billionaire Trump critic Mark Cuban, as well as Hewlett Packard Enterprise CEO Meg Whitman, one of her highest-profile Republican backers.
希拉里也邀请了一些人前来助阵,其中包括川普的批评者、亿万富翁马克·库班,以及惠普公司CEO玛格丽特·惠特曼(此人是希拉里最为高调的共和党支持者)。