Champions Ulsan Hyundai struggled to a tight 1-0 victory over Viettel FC while Beijing Guoan were held 1-1 by the United City as clubs from Southeast Asia made impressive debuts in the AFC Champions League on Saturday.
With their much better footballing pedigree, South Koreans Ulsan, who won the title in 2012 and 2020, were expected to motor past their inexperienced rivals in the Group F clash but were stunned by a fighting display put on by the Vietnamese outfit at the LEO Stadium in Pathum Thani, Thailand.
Ulsan only squeaked through in second half stoppage time and that too courtesy of an own goal by Nguyen Thanh Binh following a scramble ensuing from a corner.
The two-time winners made an attacking start and thought they had taken the lead in the sixth minute as Kim Min-jun found the net from close, only for midfielder to be ruled off-side.
Ulsan found themselves unable to create many scoring chances despite dominating ball possession as the Viettel resisted valiantly and occasionally threatened, most notably when Brazilian forward Caique forced a save from goalkeeper Jo Hyeon-woo in the first half.
The trend continued after the break but with Viettel just seconds away from grabbing a creditable point, Nguyen was forced into an error by Lukas Hinterseer much to the agony of the Vietnamese.
In Group I, Philippines champions United City took a 28th minute lead over Guoan through their German-born forward Stephan Schrock at the Bunyodkor Stadium in Tashkent.
The Chinese giants were missing several of their stars and although their young players showed great discipline they couldn't stop Schrock from scoring scored with a powerful 20-yard strike past goalkeeper Guo Quanbo.
United City, formerly known as Ceres-Negros controlled the game and could have increased their advantage later but Hikaru Minegishi and Bienvenido Maranon saw their efforts saved by goalkeeper Guo.
Their inability to finish off moves proved costly for them as Beijing found the equaliser in the 73rd minute with the 19-year-old Liang Shaowen thundering home with a spectacular 25-yard free-kick.
Another Filipino side Kaya FC however had a miserable debut as they were thrashed by Thailand's BG Pathum United, also playing their first match at this level.
Teerasil Dangda and Brazilian striker Diogo scored a brace each for Pathum United while Marwin Angeles accounted for the only goal by the Filipinos.
In a late Group I match, Japan's Kawasaki Frontale twice rallied from a goal down to edge South Korea's Daegu 3-2 in a thrilling match with Brazilian Leandro Damiao scoring a brace at the Lokomotiv Stadium in Tashkent.
Damiao first cancelled out Hwang Soon-min's eighth minute goal with his 40th minute effort and then came to his tea'’s rescue once again with another equaliser after fellow Brazilian Cesar Fernando had put the South Koreans ahead for the second time early in the second half.
Another Brazilian, Joao Schmidt, then settled matters for Kawasaki Frontale in the 55th minute as the reigning J1-League champions secured three points to begin their campaign in style.