Alexander Zverev beats John Isner 2-0 at 2018 ATP World Tour Finals

John Isner of the United States reacts during the singles match against John Isner of the United States during Day 6 of the 2018 ATP World Tour Finals at The O2 Arena in London, Britain on Nov. 16, 2018. John Isner lost 0-2. (Xinhua/Han Yan)