Andy Murray, a former world number one, had accepted a wild-card entry last year but didn't go after testing positive for COVID-19 shortly before he was due to board a charter flight to Melbourne.
The victory marks Marin Cilic's fourth title in Russia after two wins in 2014 and 2015 in Moscow.
The 34-year-old 3-time Grand Slam Champion will face Casper Rudd of Norway in the round of 16.
It was Andy Murray's second victory over a top-10 opponent in the past two weeks. He will next face Tommy Paul.
This is the first loss for British tennis player Andy Murray in 10 matches at the Austrian indoor event.
Murray lost to much younger Tsitsipas 2-6, 7-6 (7), 3-6, 6-3, 6-4, as the year's last Grand Slam tournament got underway
Andy Murray saved a set point before closing it out on his third match point in the Stockholm Open.
The contest stretched to almost five hours and Murray didn't appreciate Tsitsipas taking a medical timeout after the third set and a lengthy visit to the locker room after the fourth
Murray now heads to the US Open, where he won the first of his three Grand Slam titles in 2012
Murray's ranking slid out of the top 100 after he had two hip operations in recent years
Andy Murray remained in the doubles tournament with partner Joe Salisbury. Murray and Salisbury beat the second-seeded French team of Pierre-Hughes Herbert and...
Denis Shapovalov defeated Andy Murray,a two-time champion at Wimbledon, 6-4, 6-2, 6-2,
After wasting a pair of match points and ceding the third set, Murray defeated Basilashvili 6-4, 6-3, 5-7, 6-3
Andy Murray is making a return, while Coco Gauff hopes to make an impression again even as Wimbledon rings in a host of changes
A five-time champion of this event, Murray was a wild-card entry. He will play at Wimbledon in less than two weeks as a wild card.
The Gentlemen's and Ladies' singles winners at Wimbledon will each get USD 2.4 million, a nearly 28 percent decrease from the 2019 edition
Andy Murray will miss the French Open as he focuses on being ready for playing on grass at Queen's Club and Wimbledon
Former world number one Andy Murray will compete at the Miami Open for the first time since 2016 after being granted a wildcard.
Robin Haase took the first set in Rotterdam, but Andy Murray bounced back to seal his place in the second round
Andy Murray does not believe the next generation of tennis players are close to dethroning 18-time grand slam winner and world number one Novak Djokovic.
The announcement comes a little more than a week after Andy Murray confirmed testing positive for COVID-19 shortly before he was due to board a charter flight...
Three-time grand slam champion Murray remains in good health but is isolating at home
Having initially accepted a wildcard, Andy Murray announced he will not play at Delray Beach ahead of the Australian Open.
Andy Murray will take part in February's delayed Australian Open after being awarded a main-draw wildcard for the opening grand slam of the year.
Lewis Hamilton is set for a knighthood, reports have claimed, and Andy Murray says the F1 star's achievements make him an obvious candidate