Sindhu hardly had to break a sweat as she posted a comfortable 21-14 21-7 win over the third seeded Japanese shuttler in just 44 minutes.
It was Sindhu's third successive loss to Marin, who had won both the Super 1000 events in Thailand in January before finishing runners-up at the HSBC BWF World Tour Finals.
The 28-year-old from Kerala had spent two weeks stressing over his physical and mental health after contracting COVID-19 last November.
Earlier this month, Sindhu had attained her career-best world number two ranking after clinching her maiden India Open Super Series title.
Rio Olympic silver medallist Sindhu, who made early exits at the China Open and Korea Open, dropped to the 6th spot after five months and the former World No 2 shuttler will look to make amends at the Denmark Open and French Open.
Top shuttlers Ashwini Ponnappa and Lakshya Sen are among 20-odd Indian players who have started training at the Prakash Padukone Badminton Academy (PPBA) in Bengaluru as the sport took its first step towards resumption after the COVID-19 hiatus. Confined to their homes for more than two months due to the nationwide lockdown to contain the health crisis, the shuttlers started training at PPBA after the Sports Authority of India (SAI) laid down rules for resumption of training late last month.
All-England and World champion Carolina Marin beat Indian ace Saina Nehwal to win the 'Female Player of the Year' award in Dubai on Monday night. Besides, Saina, Marin, who won five World Superseries titles, held off competition from China's Zhao Yunlei and Bao Yixin.
Despite clinching the Macau Open title for the third time, India's ace shuttler P V Sindhu remained static at 12th position in the latest BWF world ranking released on Thursday. Saina Nehwal also held on to her number two position but a poor run of form saw K Srikanth lose a spot and slip to World No. 9.
The lack of competitions before the Olympics is a major concern for Indian shuttlers but not so much for PV Sindhu, who trusts her Korean coach Park Tae Sang to create match situations for her in training itself.
Sourabh will next face Korea's Heo Kwang Hee for a place in the men's singles final.
The unseeded Indian duo stunned local favourites Li Jun Hui and Liu Yu Chen 21-19, 21-15 in a 43-minute quarter-final clash.
Ace shuttler Saina Nehwal is currently in a tight spot in her bid for a Tokyo Olympics singles berth but a couple of good performances in the coming weeks can put her back in contention, her mentor Parupalli Kashyap said on Friday. Saina, a 2015 World Championship silver medallist and two-time Commonwealth Games champion, is racing against time to make the cut for her fourth successive Olympics.
World champion P V Sindhu frittered away a one-game lead and lost 21-16, 16-21, 19-21 to Japan's Sayaka Takahashi in 66 minutes.
After breaking into the elite zone of top-10 players, ace shuttler Saina Nehwal became the first Indian woman shuttler to be named most promising player of the year by the Badminton World Federation.
Srikanth blew two game points in the second game to lose 7-21, 20-22 to Axelsen in the men's singles summit clash.
Summary of sports events and persons who made news on Tuesday
Rankireddy and Shetty, who created history on Sunday by becoming the first Indian men's doubles pair to win a BWF Super 500 tournament, are placed ninth in the men's doubles rankings issued on Tuesday.
PV Sindhu recorded a consolation win over China's He Bingjiao in the third Group A match to end her campaign on a positive note
Reigning World champion Pramod Bhagat continued India's fine showing at the Tokyo Paralympics with a gold medal in the badminton SL3 class event, in Tokyo, on Saturday. The 33-year-old Bhagat, who is also the world No. 1 and current Asian champion, scored a 21-11, 21-16 win over Japan's Daisuke Fujihara in the first SL3 class semi-final, which lasted 36 minutes.
Verma who had shocked Malaysia's eighth seed Lee Zii Jia in the opening round, needed just 39 minutes to see off Gemke
Star India shuttler PV Sindhu was stunned by North Eastern Warriors' Michelle Li in straight games as former champions Hyderabad Hunters' made a disappointing start to its home leg of the Premier Badminton League in Hyderabad on Wednesday. World champion Sindhu suffered an 8-15, 9-15 defeat against World No 10 Canadian Li in a lop-sided women's singles contest.
Kidambi Srikanth entered the men's singles semi-finals at the Hong Kong Open after fifth seed Chen Long of China decided to quit the contest owing to an injury, in Hong Kong, on Friday.
Srikanth had last reached the quarterfinals at the Singapore Open in April.
Sindhu dished out a compact game to outwit Sayaka 21-17, 21-16 in a second round match on Thursday to set up a clash with seventh seeded Chinese He Bingjiao.
Praneeth said he needs to work on his fitness to trouble big players such as two-time world champion Kento Momota.
Lee Chong Wei's indefinite suspension for a doping violation will cost the Malaysian his top ranking with Chinese world champion Chen Long set to take over on Thursday.
India's chief national badminton coach Pullela Gopichand admitted to crammed BWF itinerary causing a problem but at the same time believes that onus is on a player of PV Sindhu's calibre to adapt to the calendar instead of complaining about it. Apart from the World Championships gold, Sindhu failed to win any other tournament last year.
Sports Minister Kiren Rijiju said the academic training at the National Centre of Excellence and Sports Auhtority of India Training Centres will also be suspended.
National camp to resume on Monday.
The Indian ace, who attained a career-best No 1 after winning the India Open at the end of March, dropped a rung in the latest Badminton World Federation (BWF) rankings, released on Thursday. Defeat in the semi-finals of the Malaysia Open Super Series Premier to reigning Olympic champion Li Xuerui of China saw the London Olympics bronze medallist drop to No 2.
The new BWF rule which makes wearing skirts on court mandatory for female shuttlers from May 1 is something that the Indian eves are finding it a bit uncomfortable.
For seven years, Lee Chong Wei, one of badminton's finest athletes, took cordyceps tablets from unmarked containers on the advice of a mysterious friend without any knowledge of how they were capsulated or stored.
Sindhu went down 15-21, 16-21 to the fourth seed
Srikanth spent the early part of the lockdown in his home town, where he was unable to train at his normal level. It was an opportunity for him to reflect on life outside badminton.
Shuttler N Sikki Reddy and physiotherapist Kiran C have tested positive for COVID-19 at the ongoing national camp, forcing the closure of the Pullela Gopichand Badminton Academy in Hyderabad for sanitisation.
Thai shuttler Bodin Issara has been suspended by his club Granular until the end of the year for his on-court punch-up with former doubles partner Maneepong Jongjit during Sunday's Canada Open final, local media reported on Saturday.
Bodin Issara was banned for two years by the Badminton Association of Thailand (BAT) for physical assault after his ugly on-court brawl with former doubles partner Maneepong Jongjit during the final of the Canada Open last week.
Satwiksairaj Rankireddy and Chirag Shetty became the first Indian pair to win a BWF Super 500 badminton tournament with a hard-fought victory over Li Jun Hui and Liu Yu Chen of China in the final of Thailand Open.
It is first final of the 2019 season for Rankireddy and Shetty, the men's doubles silver medallist at 2018 Commonwealth Games.
The London Olympics bronze medallist was trailing 4-10 in the opening game when Marin decided to withdraw from the contest.