The Swiss ace was at his elegant best as he dispatched his German opponent in just 52 minutes at the Gerry Weber Stadion, further justifying his decision to miss the entire clay-court season to focus on his grass-court campaign.
"I thought I was very calm out there, even in hard moments".
Cilic then went on to play his doubles semi-final with Marcin Matkowski against Jamie Murray and Bruno Soares, which was moved onto Court One because of the rain delays, as he aimed to become the first man to win both titles at Queen's since Pete Sampras in 1995.
Zverev, 20 and the youngest player in the world top 40, is looking to make the Halle final for the second successive year after losing to compatriot Florian Mayer in 2016. The Stuttgart defeat was the first time Federer had lost his opening match at a grass-court tournament since 2002 Wimbledon.
"I think Roger is playing really, really well", Zverev said.
Trump approves $2B sale of drones to India ahead of meeting
Such a sale of sensitive military hardware must be authorized by the State Department before being sent to Congress for review. Defence is expected to be a major agenda item when Trump hosts Modi at the White House next week.
Trump signs law to make VA more accountable for vets' care
Outdated laws kept the government from holding those who failed our veterans accountable. Critics say few employees are fired for malfeasance.
Brexit talks to focus 1st on orderly exit
Mr Hammond emphasised that leaving the EU meant the country would leave the single market and the customs union. Talks were "very constructive", however the European Union warned "the clock is ticking".
Federer has yet to drop a set in Halle this week.
Roger Federer showing his class, did not waste much time in clinching the second set and easily cruised to the winning mark.
Khachanov is a fine ball striker with a bright future in the game, but Federer on grass is one of the toughest assignments for any baseliner to face on the tour.
Zverev, who had beaten Federer in last year's semis, though had a chance to break at the start of the second set.
"I thought it was extremely close, especially that second set".
A superb dropshot put Federer 5-2 ahead and sealed Zverev's fate before he won the match on his first match point with a crosscourt volley. Kvitova responded immediately as she blasted back from 40-0 down to reel off a series of winners and once again take control of the set.